Combination Weigher

ABSTRACT

A combination weigher capable of performing a high-speed operation regardless of a characteristic of a weighed object comprises plural weighing units and a lower collecting chute and a lower collecting hopper which collect the objects which have been discharged from upper collecting hoppers of weighing units and discharge them, and a control unit. The control unit repetitively performs a process for determining a discharge combination from weighing hoppers in all weighing units, a process for causing weighing hoppers making up the discharge combination to discharge the objects, a process for causing all of the upper collecting hoppers to discharge the objects; and a process for causing the lower collecting hopper to discharge the objects.

TECHNICAL FIELD

The present invention relates to a combination weigher which feeds to apackaging machine or the like, objects to be weighed which have beenweighed.

BACKGROUND ART

Objects to be weighed, such as detergents and confectionary, which havebeen weighed to have a specified weight by a combination weigher, aretypically packaged by a packaging machine (see e.g., Patent document 1).

Such a conventional combination weigher which weighs the objects to beweighed includes, for example, plural weighing hoppers for weighing theweights of the objects to be weighed, is configured to performcombination calculation in such a manner that the weights of the objectsto be weighed held in these weighing hoppers are combined to determine acombination of weighing hoppers holding the objects to be weighed whoseweight is equal to or closest to a combination target weight, and isconfigured to discharge the objects to be weighed corresponding to thecombination to the packaging machine.

FIG. 13 shows a schematic construction of such a conventionalcombination weigher which weighs the objects to be weighed. Thecombination weigher is configured such that a control unit 30 controlsthe operation of the entire combination weigher and performs combinationcalculation. The combination weigher is constructed in such a mannerthat a center base body (body) 15 is disposed at a center of thecombination weigher, and a dispersion feeder 1 having a conical shape ismounted to an upper part of the center base body 15 to radially dispersethe objects to be weighed supplied from an external supplying device byvibration. Around the dispersion feeder 1, linear feeders 2 are providedto transfer the objects to be weighed which have been sent from thedispersion feeder 1 into respective feeding hoppers 3 by vibration.Plural feeding hoppers 3 and plural weighing hoppers 4 are disposedbelow the linear feeders 2 and are arranged in a circular form in such amanner that each feeding hopper 3 and each weighing hopper 4 correspondto the associated one of the linear feeders 2. The feeding hopper 3receives the objects to be weighed which have been sent from the linearfeeder 2, and opens its gate to feed the objects to be weighed to theweighing hopper 4 located therebelow when the weighing hopper 4 isemptied. The weighing hopper 4 is attached with a weight sensor 41 suchas a load cell. The weight sensor 41 measures the weight of the objectsto be weighed inside the weighing hopper 4. The control unit 30 performscombination calculation to select a combination (discharge combination)made up of hoppers which should discharge the objects to be weighed,from among the plural weighing hoppers 4. The weighing hoppers 4corresponding to the discharge combination discharge the objects to beweighed onto a collecting chute 6. The collecting chute 6 is providedwith a collecting hopper 7 at a discharge outlet of a bottom partthereof. The objects to be weighed which have been discharged from theweighing hoppers 4 slide down on the collecting chute 6, are held in thecollecting hopper 7 and thereafter are discharged from the collectinghopper 7.

For example, a packaging machine shown in FIG. 14 is disposed below thecollecting hopper 7. The objects to be weighed which have beendischarged from the collecting hopper 7 are introduced into an inlet(upper opening of a tube 51) of the packaging machine Whilemanufacturing package bags, the packaging machine of FIG. 14 charges theobjects to be weighed which have been discharged from the combinationweigher into the package bags and packages them.

Patent document 1: Examined Japanese Patent Application Publication No.Hei. 8-1395

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In order to increase a productivity (total number of times the objectsto be weighed are discharged to the packaging machine), the abovedescribed conventional combination weigher performs a high-speedoperation at a maximum speed, for example. However, a batch length ofthe objects to be weighed, which slide down on the collecting chute 6increases, depending on the characteristic of the objects to be weighed,such as bulky (bulk density is low) objects to be weighed, stickyobjects to be weighed, etc. This increases a time period (this timeperiod is called a batch time of the objects to be weighed on thecollecting chute 6) from when a head portion of a batch of the objectsto be weighed which have been discharged simultaneously from the pluralweighing hoppers 4 reach a discharge outlet (collecting hopper 7) of thecollecting chute 6 until a tail portion of a batch of the objects to beweighed reach the discharge outlet (collecting hopper 7) of thecollecting chute 6.

In the combination weigher, the number of the weighing hoppers 4 whichparticipate in combination calculation is increased in order to improveweighing accuracy or otherwise to maintain favorable weighing accuracyand improve a weighing speed by performing so-called a double shiftoperation, a triple shift operation, etc. In the case where the numberof weighing hoppers 4 is increased in this way, the case where acapacity (volume) of the weighing hoppers 4 is large and therefore thelength of arrangement pitch of the weighing hoppers 4 must be increased,or other cases, the arrangement shape (circular form in the example ofFIG. 13) of the weighing hoppers 4 increases. This increases the size(diameter of an upper opening and height) of the collecting chute 6increases and a transportation distance of the objects to be weighed onthe collecting chute 6 increases. Thereby, the batch length of theobjects to be weighed sliding down on the collecting chute 6 increasesand the above batch time of the objects to be weighed on the collectingchute 6 increases. Furthermore, as described above, depending on thecharacteristic of the objects to be weighed, the batch length of theobjects to be weighed sliding down on the collecting chute 6 furtherincreases and the batch time of the objects to be weighed on thecollecting chute 6 further increases.

When the batch time of the objects to be weighed on the collecting chuteincreases up to a time which is longer than a certain time (allowablebatch time) assumed, a distance between a batch of the objects to beweighed which have been discharged from the weighing hoppers 4 selectedto make up a previous discharge combination and a batch of the objectsto be weighed which have been discharged from the weighing hoppers 4selected to make up a next discharge combination becomes insufficient onthe collecting chute 6 or otherwise they are mixed thereon unless theoperation speed of the combination weigher is set slower. As a result, acorrect operation cannot be performed.

The present invention has been made to solve the above mentionedproblems, and an object of the present invention is to provide acombination weigher which is capable of reducing a batch time of objectsto be weighed on a collecting chute and of a high-speed operationregardless of a characteristic of the objects to be weighed, etc.

Means for Solving the Problem

To achieve the above mentioned objective, a combination weigher of thepresent invention comprises plural weighing units each of whichincludes: a combination hopper group including plural combinationhoppers which are arranged annularly and fed with objects to be weighed;an upper collecting chute which is disposed below the combination hoppergroup and configured to collect the objects to be weighed which havebeen discharged from the combination hoppers and to discharge theobjects to be weighed from a discharge outlet at a bottom part thereof;and an upper collecting hopper which is provided at the discharge outletof the upper collecting chute and configured to hold the objects to beweighed which have been discharged from the discharge outlet of theupper collecting chute, and to then discharge the objects to be weighed;a collecting and discharge means which is configured to collect theobjects to be weighed which have been discharged from upper collectinghoppers of the plural weighing units and to discharge the objects to beweighed; and a control means which is configured to repetitivelyperform: a combination process in which combination calculation isperformed based on weights of the objects to be weighed which are heldin the combination hoppers in combination hopper groups of all of theweighing units to determine a combination of combination hoppers holdingthe objects to be weighed whose total weight falls within apredetermined weight range and the combination is determined as adischarge combination; a first discharge process for causing thecombination hoppers making up the discharge combination determined inthe combination process to discharge the objects to be weighed; and asecond discharge process for causing the upper collecting hoppers todischarge all of the objects to be weighed which have been dischargedfrom the combination hoppers and are held in the upper collectinghoppers.

In accordance with such a configuration, since a predetermined number ofcombination hoppers included in the combination weigher are divided intoplural combination hopper groups, and plural weighing units respectivelyincluding the combination hopper groups are provided, it is possible toreduce the size of the upper collecting chute in each weighing unit, andthe transportation distance and transportation time period of theobjects to be weighed which are sliding down on each upper collectingchute, as compared to a combination weigher in which all of thecombination hoppers are arranged in a single annular form (e.g.,circular form), if the arrangement pitch and total number of thecombination hoppers are equal. In addition, it is possible to collectthe objects to be weighed which have been discharged from thecombination hoppers onto each upper collecting chute, into each uppercollecting hopper before its batch length gets large, hold therein theobjects to be weighed in a lump state, and discharge the objects to beweighed in a lump state from each upper collecting hopper to thecollecting and discharge means. As should be understood from the above,the batch time of the objects to be weighed on each upper collectingchute can be reduced, regardless of the characteristic of the objects tobe weighed, the total number of the combination hoppers, etc, therebyenabling a high-speed operation. In addition, since the transportationdistance of the objects to be weighed which are sliding down on eachupper collecting chute is short, the maximum speed at the sliding downis suppressed to a low one. Thus, the impact generated when the objectsto be weighed collide with each other, or the impact generated when theobjects to be weighed entering each upper collecting hopper collideagainst the inner wall of the upper collecting hopper is mitigated,thereby preventing the damage to the objects to be weighed. Furthermore,since the combination hoppers are arranged in the plural annular forms,the installation area of the combination weigher can be reduced, incontrast to the combination weigher in which all of the combinationhoppers are arranged in a single annular form (e.g., circular form).

The combination hopper groups in the respective weighing units mayinclude plural combination hoppers arranged along inner sides ofcircumferences of plural different imaginary circles.

In this case, when the number of weighing units is expressed as N, thediameter of the imaginary circle in each weighing unit can be made 1/Nof the diameter of a single imaginary circle formed by all of thecombination hoppers arranged along the inner side of the circumferenceof the imaginary circle in the conventional combination weigher.Therefore, the diameter of each upper collecting chute can be reduced toapproximately 1/N of the diameter of the collecting chute in theconventional combination weigher, and the installation area of thecombination weigher can be reduced to approximately 1/N of theinstallation area of the conventional combination weigher.

The combination hopper groups may be configured such that the differentimaginary circles may partially overlap with each other, and thecombination hopper is not disposed in circular-arc regions of theimaginary circles corresponding to an overlapping region of theimaginary circles.

In this case, since no combination hopper is disposed in the regionwhere the weighing units are adjacent each other. This thereforefacilitates a dismounting work or a mounting work of the combinationhoppers when the combination hoppers are cleaned, repaired, etc.

The control means may be configured to perform the second dischargeprocess such that all of the upper collecting hoppers discharge theobjects to be weighed simultaneously.

Since all of the upper collecting hoppers operate at the same timing,the upper collecting hoppers can be easily controlled.

The collecting and discharge means may include a single lower collectingchute which is disposed below the upper collecting hoppers andconfigured to collect the objects to be weighed which have beendischarged from all of the upper collecting hoppers and to discharge theobjects to be weighed from a discharge outlet at a bottom part thereofto a packaging machine inlet. This configuration is referred to as atwo-stage chute configuration.

In accordance with such a configuration, by reducing the size of theupper and lower collecting chutes, it is possible to reduce thetransportation distance and transportation time period of the objects tobe weighed which are sliding down on the upper and lower collectingchutes. It is possible to collect the objects to be weighed which havebeen discharged from the combination hoppers onto the upper collectingchute, into the upper collecting hopper, before its batch length getslarge, to hold therein the objects to be weighed in a lump state, and todischarge the objects to be weighed in a lump state from the uppercollecting hopper to the lower collecting chute. In addition, it ispossible to discharge the objects to be weighed which have beendischarged to the lower collecting chute, from the discharge outletthereof, to the packaging machine inlet, before its batch length getslarge. Therefore, the batch time of the objects to be weighed on theupper and lower collecting chutes can be reduced, regardless of thecharacteristic of the objects to be weighed, the total number of thecombination hoppers, etc, thereby enabling a high-speed operation. Sincethe transportation distance over which the objects to be weighed slidedown on the upper and lower collecting chutes is short, the maximumspeed at the sliding down is suppressed to a low one. Thus, the impactgenerated when the objects to be weighed collide with each other, or theimpact generated when the objects entering the upper collecting hoppercollide against the inner wall of the upper collecting hopper ismitigated, thereby preventing the damage to the objects to be weighed.

The collecting and discharge means may include plural intermediatecollecting chutes which are disposed below the upper collecting hoppersand configured to collect the objects to be weighed which have beendischarged from plural different upper collecting hoppers and todischarge the objects to be weighed from discharge outlets at bottomparts thereof, plural intermediate collecting hoppers which arerespectively provided at discharge outlets of the respectiveintermediate collecting chutes and to hold the objects to be weighedwhich have been discharged from the discharge outlets of theintermediate collecting chutes and to then discharge the objects to beweighed; and a single lower collecting chute which is disposed below theintermediate collecting hoppers and configured to collect the objects tobe weighed which have been discharged from all of the intermediatecollecting hoppers and to discharge the objects to be weighed from adischarge outlet at a bottom part thereof to a packaging machine inlet.This configuration is referred to as a three-stage chute configuration.

In accordance with such a configuration, by reducing the size of theupper, intermediate and lower collecting chutes, it is possible toreduce the transportation distance and transportation time period of theobjects to be weighed which are sliding down on the upper, intermediateand lower collecting chutes. It is possible to collect the objects to beweighed which have been discharged from the combination hoppers to theupper collecting chute, into the upper collecting hopper, before itsbatch length gets large, hold therein the objects to be weighed in alump state, and discharge the objects to be weighed in a lump state fromthe upper collecting hopper to the intermediate collecting chute. Inaddition, it is possible to collect into the intermediate collectinghopper, the objects to be weighed which have been discharged to theintermediate collecting chute before its batch length gets large, holdtherein the objects to be weighed in a lump state, and discharge theobjects to be weighed in a lump state from the intermediate collectinghopper to the lower collecting chute. In addition, it is possible todischarge the objects to be weighed which have been discharged to thelower collecting chute, from the discharge outlet thereof, to thepackaging machine inlet, before its batch length gets large. Therefore,the batch time of the objects to be weighed on the upper, intermediateand lower collecting chutes can be reduced, regardless of thecharacteristic of the objects to be weighed, the total number of thecombination hoppers, etc, thereby enabling a high-speed operation. Sincethe transportation distance over which the objects to be weighed slidedown on the upper, intermediate and lower collecting chutes is short,the maximum speed at the sliding down is suppressed to a low one. Thus,the impact generated when the objects to be weighed collide with eachother, or the impact generated when the objects entering the upper andintermediate collecting hoppers collide against the inner walls of theupper and intermediate collecting hoppers is mitigated, therebypreventing the damage to the objects to be weighed.

The collecting and discharge means may further include a lowercollecting hopper which is provided at a discharge outlet of the lowercollecting chute and configured to hold the objects to be weighed whichhave been discharged from the discharge outlet of the lower collectingchute and to then discharge the objects to be weighed.

In accordance with such a configuration, it is possible to collect intothe lower collecting hopper, the objects to be weighed which have beendischarged onto the lower collecting chute hand have a certain batchlength (length), hold therein the objects to be weighed, and dischargethe objects to be weighed from the lower collecting hopper to thepackaging machine inlet in a lump state.

The collecting and discharge means may further include collecting chutesin plural stages from second stage to p-th (p: integer of 4 or more)stage which are disposed below a first-stage collecting chute consistingof the upper collecting chutes, and collecting hoppers which arerespectively provided at discharge outlets of bottom parts of thecollecting chutes in the second stage to (p−1)-th stage, configured tohold the objects to be weighed which have been discharged from thedischarge outlets at the bottom parts of the collecting chutes and tothen discharge the objects to be weighed, the collecting chute in q-th(q: integer in a range from 2 to p) stage is configured to collect theobjects to be weighed which have been discharged from collecting hoppersrespectively provided at discharge outlets of plural collecting chutesin (q−1)-th stage and to discharge the objects to be weighed from adischarge outlets at a bottom part thereof, and the objects to beweighed which have been discharged from the discharge outlet at thebottom part of the collecting chute in the p-th stage may be fed to thepackaging machine inlet. This configuration is referred to as amulti-stage chute configuration.

In accordance with such a configuration, by reducing the size of thecollecting chutes in first stage (upper stage) to p-th stage, it ispossible to reduce the transportation distance and transportation timeperiod of the objects to be weighed which are sliding down on eachcollecting chute. It is possible to collect the objects to be weighedwhich have been discharged to the collecting chutes in first stage to(p−1)-th stage, into the collecting hoppers provided at the respectivecollecting chutes, before its batch length gets large, discharge theobjects to be weighed in a lump state from each collecting hopper to thecollecting chute in a subsequent stage, and discharge the objects to beweighed which have been discharged to the collecting chute in the p-thstage which is a lowermost stage, from the discharge outlet thereof, tothe packaging machine inlet, before its batch length gets large.Therefore, the batch time of the objects to be weighed on eachcollecting chute can be reduced, regardless of the characteristic of theobjects to be weighed, the total number of the combination hoppers, etcthereby enabling a high-speed operation. Since the transportationdistance over which the objects to be weighed slide down on eachcollecting chute is short, the maximum speed at the sliding down issuppressed to a low one. Thus, the impact generated when the objects tobe weighed collide with each other, or the impact generated when theobjects entering the collecting hopper collide against the inner wall ofthe collecting hopper is mitigated, thereby preventing the damage to theobjects to be weighed.

The collecting and discharge means may further include a collectinghopper which is provided at a discharge outlet of the collecting chutein the p-th stage and configured to hold the objects to be weighed whichhave been discharged from the discharge outlet of the collecting chutein the p-th stage and to then discharge the objects to be weighed.

In accordance with such a configuration, the objects to be weighed canbe discharged from the collecting hopper which is provided at thedischarge outlet of the collecting chute in the p-th stage to thepackaging machine inlet in a lump state.

The upper collecting hopper may be configured to discharge the objectsto be weighed selectively in a first direction or in a second direction.The collecting and discharge means may include a first lower collectingchute which is disposed below the upper collecting hoppers andconfigured to collect the objects to be weighed which have beendischarged from all of the upper collecting hoppers in the firstdirection and to discharge the objects to be weighed from a dischargeoutlet at a bottom part thereof to a first packaging machine inlet, anda second lower collecting chute which is disposed below the uppercollecting hoppers and configured to collect the objects to be weighedwhich have been discharged from all of the upper collecting hoppers inthe second direction and to discharge the objects to be weighed from adischarge outlet at a bottom part thereof to a second packaging machineinlet. The control means may be configured to cause all of the uppercollecting hoppers to discharge the objects to be weighed alternately inthe first and second directions, when repetitively performing the seconddischarge process. This configuration is referred to as a two-directiondischarge configuration.

In accordance with such a configuration, it is possible to discharge theobjects to be weighed to the first and second packaging machine inletsalternately. In addition, the same advantage as that of the two-stagechute configuration is achieved.

The upper collecting hopper may be configured to discharge the objectsto be weighed selectively in a first direction or in a second direction.The collecting and discharge means may include plural first intermediatecollecting chutes which are disposed below the upper collecting hoppersand configured to collect the objects to be weighed which have beendischarged from plural different upper collecting hoppers in the firstdirection and to discharge the objects to be weighed from dischargeoutlets at bottom parts thereof, plural second intermediate collectingchutes which are disposed below the upper collecting hoppers andconfigured to collect the objects to be weighed which have beendischarged from plural different upper collecting hoppers in the seconddirection and to discharge the objects to be weighed from dischargeoutlets at bottom parts thereof; plural first intermediate collectinghoppers which are respectively provided at the discharge outlets of thefirst intermediate collecting chutes and configured to hold the objectsto be weighed which have been discharged from the discharge outlets ofthe first intermediate collecting chutes and to then discharge theobjects to be weighed; plural second intermediate collecting hopperswhich are respectively provided at the discharge outlets of the secondintermediate collecting chutes and configured to hold the objects to beweighed which have been discharged from the discharge outlets of thesecond intermediate collecting chutes and to then discharge the objectsto be weighed; a first lower collecting chute which is disposed belowthe first intermediate collecting hoppers and configured to collect theobjects to be weighed which have been discharged from all of the firstintermediate collecting hoppers and to discharge the objects to beweighed from a discharge outlet at a bottom part thereof to a firstpackaging machine inlet; and a second lower collecting chute which isdisposed below the second intermediate collecting hoppers and configuredto collect the objects to be weighed which have been discharged from allof the second intermediate collecting hoppers and to discharge theobjects to be weighed from a discharge outlet at a bottom part thereofto a second packaging machine inlet. The control means may be configuredto cause all of the upper collecting hoppers to discharge the objects tobe weighed alternately in the first and second directions, whenrepetitively performing the second discharge process.

In accordance with such a configuration, it is possible to discharge theobjects to be weighed to the first and second packaging machine inletsalternately. In addition, the same advantage as that of the three-stagechute configuration is achieved.

The collecting and discharge means may include plural intermediatecollecting chutes which are disposed below the upper collecting hoppersand configured to collect the objects to be weighed which have beendischarged from plural different upper collecting hoppers and todischarge the objects to be weighed from discharge outlets at bottomparts thereof, plural intermediate collecting hoppers which arerespectively provided at the discharge outlets of the intermediatecollecting chutes and configured to hold the objects to be weighed whichhave been discharged from the discharge outlets of the intermediatecollecting chutes and to then discharge the objects to be weighedselectively in a first direction or in a second direction; a first lowercollecting chute which is disposed below the intermediate collectinghoppers and configured to collect the objects to be weighed which havebeen discharged from all of the intermediate collecting hoppers in thefirst direction and to discharge the objects to be weighed from adischarge outlet at a bottom part thereof to a first packaging machineinlet; a second lower collecting chute which is disposed below theintermediate collecting hoppers and configured to collect the objects tobe weighed which have been discharged from all of the intermediatecollecting hoppers in the second direction and to discharge the objectsto be weighed from a discharge outlet at a bottom part thereof to asecond packaging machine inlet. The control means may be configured tocause all of the intermediate collecting hoppers to discharge theobjects to be weighed alternately in the first and second directions,when repetitively performing the second discharge process.

In accordance with such a configuration, it is possible to discharge theobjects to be weighed to the first and second packaging machine inletsalternately. In addition, the same advantage as that of the three-stagechute configuration is achieved.

The collecting and discharge means may further include two lowercollecting hoppers which are provided at discharge outlets of the firstand second lower collecting chutes, respectively, and configured to holdthe objects to be weighed which have been discharged from the dischargeoutlets of the lower collecting chutes and to then discharge the objectsto be weighed.

In accordance with such a configuration, the objects to be weighed whichhave been discharged onto the first and second lower collecting chutesand have a certain batch length (length) can be collected into and heldin the associated lower collecting hoppers, and can be discharged in alump state from the lower collecting hoppers to the packaging machineinlets.

The upper collecting hopper may be configured to discharge the objectsto be weighed selectively in a first direction or in a second direction.The collecting and discharge means may further include collecting chutesin plural stages from second stage to p-th (p: integer of 4 or more)stage which are disposed below a first-stage collecting chute consistingof the upper collecting chutes, and collecting hoppers which arerespectively provided at discharge outlets at bottom parts of thecollecting chutes in the second stage to (p−1)-th stage, and configuredto hold the objects to be weighed which have been discharged from thedischarge outlets at the bottom parts of the respective collectingchutes and to then discharge the objects to be weighed, the collectingchute in q-th (q: integer in a range from 2 to p) stage is configured tocollect the objects to be weighed which have been discharged from thecollecting hoppers provided at the discharge outlets of pluralcollecting chutes in (q−1)-th stage and to discharge the objects to beweighed from a discharge outlet at a bottom part thereof, the collectingchutes in second stage to p-th stage are disposed so as to form a firstdischarge path for guiding the objects to be weighed which have beendischarged from the upper collecting hopper in the first direction to afirst packaging machine inlet and a second discharge path for guidingthe objects to be weighed which have been discharged from the uppercollecting hopper in the second direction to a second packaging machineinlet. The control means may be configured to cause all of the uppercollecting hoppers to discharge the objects to be weighed alternately inthe first and second directions when repetitively performing the seconddischarge process.

In accordance with such a configuration, it is possible to discharge theobjects to be weighed to the first and second packaging machine inletsalternately. In addition, the same advantage as that of the multi-stagechute configuration is achieved.

The collecting and discharge means may further include collecting chutesin plural stages from second stage to p-th (p: integer of 4 or more)stage which are disposed below a first-stage collecting chute consistingof the upper collecting chutes, and collecting hoppers which arerespectively provided at discharge outlets of bottom parts of thecollecting chutes in the second stage to (p−1)-th stage, and configuredto hold the objects to be weighed which have been discharged from thedischarge outlets at the bottom parts of the respective collectingchutes, and to then discharge the objects to be weighed, the collectingchute in q-th (q: integer in a range from 2 to p) stage, among thecollecting chutes in the plural stages, is configured to collect theobjects to be weighed which have been discharged from the collectinghoppers respectively provided at discharge outlets of plural collectingchutes in (q−1)-th stage and to discharge the objects to be weighed froma discharge outlet at a bottom part thereof, k-th stage collectinghopper which is a collecting hopper provided at a discharge outlet ofthe collecting chute in k-th (k: one integer in a range from 2 to p−1)stage is configured to discharge the objects to be weighed selectivelyin the first direction or in the second direction, the collecting chutesin (k+1)-th stage to p-th stage are disposed so as to form a firstdischarge path for guiding the objects to be weighed which have beendischarged from the k-th stage collecting hopper in the first directionto a first packaging machine inlet and a second discharge path forguiding the objects to be weighed which have been discharged from thek-th stage collecting hopper in the second direction to a secondpackaging machine inlet. The control means may be configured to causeall of the collecting hoppers in k-th stage to discharge the objects tobe weighed alternately in the first and second directions whenrepetitively performing the second discharge process.

In accordance with such a configuration, it is possible to discharge theobjects to be weighed to the first and second packaging machine inletsalternately. In addition, the same advantage as that of the multi-stagechute configuration is achieved.

The collecting and discharge means may include a collecting hopper whichis provided at a discharge outlet of the collecting chute in p-th stageand configured to hold the objects to be weighed which have beendischarged from the discharge outlet of the collecting chute in p-thstage and to then discharge the objects to be weighed.

In accordance with such a configuration, it is possible to discharge theobjects to be weighed in a lump state from the collecting hopperprovided at the discharge outlet of the collecting chute in p-th stageto the packaging machine inlet.

The control means may be configured to repetitively perform thecombination process in such a manner that, in n (n: predetermined pluralnumber) successive combination processes, the combination calculation isperformed based on weights of objects to be weighed which are held incombination hoppers which are not selected to make up a dischargecombination determined in previous combination processes, in a next andearliest combination process.

In accordance with such a configuration, since the combination processcan be performed n times and the objects to be weighed can be dischargedn times within the actual weighing cycle time, productivity within acertain time period can be improved. In the case of n=2, so-called adouble shift operation takes place, while in the case of n=3, so-calleda triple shift operation takes place.

The control means may be configured to determine the dischargecombination such that the discharge combination includes the combinationhoppers belonging to at least two combination hopper groups.

In accordance with such a configuration, since the objects to be weighedwhich have been discharged from the combination hoppers making up thedischarge combination are discharged to at least two upper collectingchutes and collected into at least two upper collecting hoppersseparately, the size (volume) of the upper collecting hopper can bereduced.

The control means may be configured to repetitively perform a series ofprocesses including the combination process, the first discharge processand the second discharge process, in a predetermined cycle, and theupper collecting chute may be configured such that a time period thatelapses from when the combination hoppers making up the dischargecombination determined in the combination process start discharging ofthe objects to be weighed until all of the discharged objects to beweighed pass through on the upper collecting chute and are fed to theupper collecting hopper is not longer than 1.1 times as long as thepredetermined cycle.

In accordance with such a configuration, it is possible to suppress thebatch time of the objects to be weighed on the upper collecting chute toa certain time or less. The objects to be weighed are discharged fromthe combination hoppers selected to make up the discharge combination inevery predetermined cycle. After all of the objects to be weighed whichhave been discharged from the combination hoppers selected to make up acertain discharge combination slide down on the upper collecting chute,the objects to be weighed are discharged from the combination hoppersselected to make up a next discharge combination. This makes it possibleto surely prevent mixing between a previous batch of objects to beweighed and a next batch of objects to be weighed on the uppercollecting chute and to discharge the objects to be weighed from theupper collecting hopper in every predetermine cycle.

In aforesaid two-stage chute configuration, the control means may beconfigured to repetitively perform a series of processes including thecombination process, the first discharge process and the seconddischarge process, in a predetermined cycle, and the upper collectingchute may be configured such that a time period that elapses from whenthe combination hoppers making up the discharge combination determinedin the combination process start discharging of the objects to beweighed until all of the discharged objects to be weighed pass throughon the upper collecting chute and are fed to the upper collecting hopperis not longer than 1.1 times as long as the predetermined cycle, and thelower collecting chute may be configured such that a time period thatelapses from when the upper collecting hopper starts discharging of theobjects to be weighed until all of the discharged objects to be weighedpass through on the lower collecting chute and are discharged from adischarge outlet at a bottom part of the lower collecting chute is notlonger than 1.1 times as long as the predetermined cycle.

In accordance with such a configuration, it is possible to suppress thebatch time of the objects to be weighed on the upper and lowercollecting chutes to a certain time or less. The objects to be weighedare discharged from the combination hoppers selected to make up thedischarge combination in every predetermined cycle. After all of theobjects to be weighed which have been discharged from the combinationhoppers selected to make up a certain combination slide down on theupper collecting chute, the objects to be weighed are discharged fromthe combination hoppers selected to make up a next dischargecombination. This makes it possible to surely prevent mixing between aprevious batch of objects to be weighed and a next batch of objects tobe weighed on the upper collecting chute and to discharge the objects tobe weighed from the upper collecting hopper in every predetermine cycle.In addition, after all of the objects to be weighed which have beendischarged from the upper collecting hopper slide down on the lowercollecting chute, a next batch of the objects to be weighed aredischarged from the upper collecting hopper. This makes it possible tosurely prevent mixing between a previous batch of objects to be weighedand a next batch of objects to be weighed on the lower collecting chuteand to discharge the objects to be weighed from the discharge outlet ofthe lower collecting chute in every predetermine cycle.

In aforesaid three-stage chute configuration, the control means may beconfigured to repetitively perform a series of processes including thecombination process, the first discharge process and the seconddischarge process, in a predetermined cycle, and the upper collectingchute may be configured such that a time period that elapses from whenthe combination hoppers making up the discharge combination determinedin the combination process start discharging of the objects to beweighed until all of the discharged objects to be weighed pass throughon the upper collecting chute and are fed to the upper collecting hopperis not longer than 1.1 times as long as the predetermined cycle, theintermediate collecting chute may be configured such that a time periodthat elapses from when the upper collecting hopper starts dischargingthe objects to be weighed until all of the discharged objects to beweighed pass through on the intermediate collecting chute and are fed tothe intermediate collecting hopper is not longer than 1.1 times as longas the predetermined cycle, and the lower collecting chute may beconfigured such that a time period that elapses from when theintermediate collecting hopper starts discharging of the objects to beweighed until all of the discharged objects to be weighed pass throughon the lower collecting chute and are discharged from a discharge outletat a bottom part of the lower collecting chute is not longer than 1.1times as long as the predetermined cycle.

In accordance with such a configuration, it is possible to suppress thebatch time of the objects to be weighed on the upper, intermediate andlower collecting chutes to a certain time or less. The objects to beweighed are discharged from the combination hoppers selected to make upthe discharge combination in every predetermined cycle. After all of theobjects to be weighed which have been discharged from the combinationhoppers selected to make up a certain discharge combination slide downon the upper collecting chute, the objects to be weighed are dischargedfrom the combination hoppers selected to make up a next dischargecombination. This makes it possible to surely prevent mixing between aprevious batch of objects to be weighed and a next batch of objects tobe weighed on the upper collecting chute and to discharge the objects tobe weighed from the upper collecting hopper in every predetermine cycle.In addition, after all of the objects to be weighed which have beendischarged from the upper collecting hopper slide down on theintermediate collecting chute, a next batch of the objects to be weighedare discharged from the upper collecting hopper. This makes it possibleto surely prevent mixing between a previous batch of objects to beweighed and a next batch of objects to be weighed on the intermediatecollecting chute and to discharge the objects to be weighed from theintermediate collecting hopper in every predetermine cycle. In addition,after all of the objects to be weighed which have been discharged fromthe intermediate collecting hopper slide down on the lower collectingchute, a next batch of the objects to be weighed are discharged from theintermediate collecting hopper. This makes it possible to surely preventmixing between a previous batch of objects to be weighed and a nextbatch of objects to be weighed on the lower collecting chute and todischarge the objects to be weighed from the discharge outlet of thelower collecting chute in every predetermine cycle.

In aforesaid triple-stage chute configuration, the control means may beconfigured to repetitively perform a series of processes including thecombination process, the first discharge process and the seconddischarge process, in a predetermined cycle, and the first-stagecollecting chute may be configured such that a time period that elapsesfrom when the combination hoppers making up the discharge combinationdetermined in the combination process start discharging of the objectsto be weighed until all of the discharged objects to be weighed passthrough on the first-stage collecting chute and are fed to the uppercollecting hopper is not longer than 1.1 times as long as thepredetermined cycle, the collecting chute in q-th stage may beconfigured such that a time period that elapses from when the collectinghopper provided at the discharge outlet of the collecting chute in(q−1)-th stage starts discharging of the objects to be weighed until allof the discharged objects to be weighed pass through on the collectingchute in q-th stage and are discharged from a discharge outlet at abottom part of the collecting chute in q-th stage is not longer than 1.1times as long as the predetermined cycle.

In accordance with such a configuration, it is possible to suppress thebatch time of the objects to be weighed on the collecting chutes infirst stage (upper) to p-th stage to a certain time or less. The objectsto be weighed are discharged from the combination hoppers selected tomake up the discharge combination in every predetermined cycle. Afterall of the objects to be weighed which have been discharged from thecombination hoppers selected to make up a discharge combination slidedown on the first-stage (upper) collecting chute, the objects to beweighed are discharged from the combination hoppers selected to make upa next discharge combination. This makes it possible to surely preventmixing between a previous batch of objects to be weighed and a nextbatch of objects to be weighed on the first-stage (upper) collectingchute and to discharge the objects to be weighed from the uppercollecting hopper in every predetermine cycle. In addition, after all ofthe objects to be weighed which have been discharged from the collectinghopper provided at the discharge outlet of the collecting chute in(q−1)-th stage slide down on the collecting chute in q-th stage, a nextbatch of the objects to be weighed are discharged from the abovementioned collecting hopper. This makes it possible to surely preventmixing between a previous batch of objects to be weighed and a nextbatch of objects to be weighed on the collecting chute in q-th stage andto discharge the objects to be weighed from the discharge outlet of thecollecting chute in q-th stage in every predetermine cycle.

In aforesaid two-direction discharge configuration, the control meansmay be configured to repetitively perform a series of processesincluding the combination process, the first discharge process and thesecond discharge process, in a predetermined cycle, and the uppercollecting chute may be configured such that a time period that elapsesfrom when the combination hoppers making up the discharge combinationdetermined in the combination process start discharging of the objectsto be weighed until all of the discharged objects to be weighed passthrough on the upper collecting chute and are fed to the uppercollecting hopper is not longer than 1.1 times as long as thepredetermined cycle, the first lower collecting chute may be configuredsuch that a time period that elapses from when the upper collectinghopper starts discharging of the objects to be weighed in the firstdirection until all of the discharged objects to be weighed pass throughon the first lower collecting chute and are discharged from a dischargeoutlet at a bottom part of the first lower collecting chute is notlonger than (2×1.1) times as long as the predetermined cycle, and thesecond lower collecting chute may be configured such that a time periodthat elapses from when the upper collecting hopper starts discharging ofthe objects to be weighed in the second direction until all of thedischarged objects to be weighed pass through on the second lowercollecting chute and are discharged from a discharge outlet at a bottompart of the second lower collecting chute is not longer than (2×1.1)times as long as the predetermined cycle.

In accordance with such a configuration, it is possible to suppress thebatch time of the objects to be weighed on the upper and lowercollecting chutes to a certain time or less. The objects to be weighedare discharged from the combination hoppers selected to make up thedischarge combination in every predetermined cycle. After all of theobjects to be weighed which have been discharged from the combinationhoppers selected to make up a discharge combination slide down on theupper collecting chute, the objects to be weighed are discharged fromthe combination hoppers selected to make up a next dischargecombination. This makes it possible to surely prevent mixing between aprevious batch of objects to be weighed and a next batch of objects tobe weighed on the upper collecting chute and to discharge the objects tobe weighed from the upper collecting hopper alternately to the firstlower collecting chute and to the second lower collecting chute in everypredetermine cycle. Therefore, the objects to be weighed are dischargedfrom the upper collecting hopper to the first lower collecting chute andto the second lower collecting chute once every time which is twice aslong as the predetermined cycle. After all of the objects to be weighedof a previous batch which have been discharged from the upper collectinghopper slide down on each of the first and second lower collectingchutes, a next batch of the objects to be weighed are discharged fromthe upper collecting hopper to the same. This makes it possible tosurely prevent mixing between a previous batch of objects to be weighedand a next batch of objects to be weighed on the first and second lowercollecting chutes and to discharge the objects to be weighed from thedischarge outlets of the first and second lower collecting chutes everytime which is twice as long as the predetermined cycle.

The predetermined cycle may be set to a time which is 1/k (k: 1 orplural number) of an actual weighing cycle time which is a time periodfrom when the combination hoppers making up the discharge combinationdetermined in the combination process start discharging of the objectsto be weighed until a time just before a procedure in which thecombination hoppers making up the discharge combination are next fedwith the objects to be weighed, then a next and earliest combinationprocess is performed using at least weights of the objects to be weighedheld in the combination hoppers making up the discharge combination, andcombination hoppers making up a discharge combination determined in thenext and earliest combination process start discharging of the objectsto be weighed.

For example, the configuration in the case of k=1 is a configuration forcausing the combination weigher to perform so-called a single shiftoperation, the configuration in the case of k=2 is a configuration forcausing the combination weigher to perform so-called a double shiftoperation, and the configuration in the case of k=3 is a configurationfor causing the combination weigher to perform so-called a triple shiftoperation.

The actual weighing cycle time may be equal to an ideal weighing cycletime which is a time period from when the combination hoppers making upthe discharge combination determined in the combination process startdischarging of the objects to be weighed until the combination hoppersmaking up the discharge combination are next fed with the objects to beweighed, then a next and earliest combination process is performed usingat least weights of the objects to be weighed held in the combinationhoppers making up the discharge combination, and a discharge combinationis determined in the next and earliest combination process.

In accordance with such a configuration, the combination weigher is ableto exhibit a highest weighing capability (speed).

It is preferable that when the number of the weighing units is x, thetotal number of the combination hoppers included in all of the weighingunits is y, and y/x is an integer, the combination hopper group in eachof the weighing units may be configured to consist of y/x combinationhoppers, and when (z−1)<(y/x)<z (z: integer) is satisfied, thecombination hopper group in a part of all of the weighing units may beconfigured to consist of z combination hoppers and the combinationhopper group in the weighing unit other than the part of the all of theweighing units may be configured to consist of (z−1) combinationhoppers.

In accordance with such a configuration, when the combination hoppergroup in each weighing unit includes y/x combination hoppers, it ispossible to equalize the sizes of the upper collecting chutes in therespective weighing units, the transportation distances andtransportation time periods of the objects to be weighed sliding down onthe respective upper collecting chutes. When the combination hoppergroup in a part of all of the weighing units includes z combinationhoppers and the combination hopper group in other weighing unit includes(z−1) combination hoppers, it is possible to equalize the transportationdistances and transportation time periods of the objects to be weighedsliding down on the respective upper collecting chutes by setting thesize of the upper collecting chute in other weighing unit equal to thesize of the upper collecting chute in the part of all of the weighingunits and by arranging the combination hoppers with respect to the uppercollecting chute in other weighing unit in the same manner that thecombination hoppers are arranged with respect to the upper collectingchute in the part of all of the weighing units.

The respective upper collecting chutes may be arranged without a gapbetween them.

In accordance with such a configuration, it is possible to minimize theinstallation area of the combination weigher. In addition, it ispossible to reduce the size of the collecting and discharge means forcollecting the objects to be weighed which are discharged from the uppercollecting hopper, for example, the size of the lower collecting chutein the two-stage chute configuration, the intermediate collecting chutein the three-stage chute configuration, etc. This contributes toreduction of the transportation distance and transportation time periodof the objects to be weighed sliding down on these collecting chutes.

The respective upper collecting chutes may be arranged with a gapbetween them.

In accordance with such a configuration, it is possible to reduce theinstallation area of the combination weigher by arranging the uppercollecting chutes adjacent each other. In addition, it is possible toreduce the size of the collecting and discharge means for collecting theobjects to be weighed which are discharged from the upper collectinghopper, for example, the size of the lower collecting chute in thetwo-stage chute configuration, the intermediate collecting chute in thethree-stage chute configuration, etc. This contributes to reduction ofthe transportation distance and transportation time period of theobjects to be weighed sliding down on these collecting chutes.Furthermore, by providing a small gap between the upper collectingchutes, work such as cleaning is facilitated.

The imaginary circles may be configured to be in contact with eachother. In accordance with such a configuration, it is possible to reducethe installation area of the combination weigher. In addition, it ispossible to reduce the size of the collecting and discharge means forcollecting the objects to be weighed which are discharged from the uppercollecting hopper, for example, the size of the lower collecting chutein the two-stage chute configuration, the intermediate collecting chutein the three-stage chute configuration, etc. This contributes toreduction of the transportation distance and transportation time periodof the objects to be weighed sliding down on these collecting chutes.

The same kinds of objects to be weighed may be fed to the combinationhoppers in all of the weighing units.

EFFECTS OF THE INVENTION

The present invention has the above described configuration and achievesan advantage that the combination weigher can reduce the batch time ofthe objects to be weighed on the collecting chutes and perform ahigh-speed operation regardless of a characteristic of the objects to beweighed, etc.

The above object, other objects, features, and advantages of the presentinvention will be apparent by the following detailed description ofpreferred Embodiment of the inventions, with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 (a) is a schematic partial cross-sectional view of a combinationweigher according Embodiment 1 of the present invention, as viewed fromthe front, and FIG. 1( b) is a schematic view of upper collecting chutesand weighing hoppers of the combination weigher, as viewed from above.

FIG. 2 is a timing chart showing an example of the opening and closingoperation of the gates of collecting hoppers, the opening and closingoperation of the gates of the weighing hoppers, and the operation of ahorizontal sealing device of a packaging machine, in a case where thecombination weigher of Embodiment 1 of the present invention isconfigured to perform a single shift operation.

FIG. 3 is a timing chart showing an example of the opening and closingoperation of the gates of collecting hoppers, the opening and closingoperation of the gates of the weighing hoppers, and the operation of thehorizontal sealing device of the packaging machine, in a case where thecombination weigher of Embodiment 1 of the present invention isconfigured to perform a double shift operation.

FIG. 4( a) is a schematic view showing a specific positionalrelationship between the weighing hopper and the upper collecting chuteand the configuration of the gate of the weighing hopper in Embodiment 1of the present invention, and FIG. 4( b) is a schematic view showing aspecific positional relationship between the upper collecting hopper andthe lower collecting chute and the configuration of the gate of theupper collecting hopper.

FIG. 5( a) is a schematic view showing an exemplary falling state of theobjects to be weighed inside the combination weigher and the packagingmachine in Embodiment 1 of the present invention, and FIG. 5( b) is aschematic view showing an exemplary falling state of the objects to beweighed inside the conventional combination weigher and the packagingmachine shown in FIG. 13.

FIGS. 6( a) and 6(b) are schematic views of the upper collecting chutesand the weighing hoppers of a combination weigher including threeweighing units in Embodiment 1 of the present invention, as viewed fromabove.

FIG. 7 is a schematic view of the upper collecting chutes and theweighing hoppers of a combination weigher including three weighing unitsin Embodiment 1 of the present invention, as viewed from above, showinga modification of the arrangement of the weighing hoppers.

FIG. 8 (a) is a schematic view of upper collecting chutes and weighinghoppers of a combination weigher according Embodiment 2 of the presentinvention, as viewed from above, and FIG. 8( b) is a schematic view ofupper, intermediate and lower collecting chutes of the combinationweigher, as viewed from the front.

FIG. 9 is a timing chart showing an example of the opening and closingoperation of the gates of collecting hoppers, the opening and closingoperation of the gates of the weighing hoppers, and the operation of thehorizontal sealing device of the packaging machine, in a case where thecombination weigher of Embodiment 2 of the present invention isconfigured to perform a triple shift operation.

FIG. 10 is a schematic view of upper collecting chutes and weighinghoppers of a combination weigher, showing a modification of the weighingunits of FIG. 1, as viewed from above.

FIG. 11 is a plan view showing a configuration of lower collectingchutes in a case where the objects to be weighed which have beendischarged from the combination weigher are fed to two packaging machineinlets.

FIGS. 12 (a) to 12(d) are schematic views showing other examples ofhoppers used in the combination weigher of Embodiment of the presentinvention.

FIG. 13 is a partial cross-sectional schematic view of the conventionalcombination weigher as viewed from the front.

FIG. 14 is a schematic view showing an exemplary packaging machinedisposed below the combination weigher.

EXPLANATION OF REFERENCE NUMERALS

-   1. dispersion feeder-   2. linear feeder-   3. feeding hopper-   4. weighing hopper-   5. memory hopper-   6A-6D. upper collecting chutes-   7A-7D. upper collecting hoppers-   8. lower collecting chute-   9. lower collecting hopper-   10 a, 10 b. intermediate collecting chutes-   11 a, 11 b. intermediate collecting hoppers-   20. control unit

BEST MODE FOR CARRYING OUT EMBODIMENT

Hereinafter, preferred embodiments of the present invention will bedescribed with reference to the drawings.

Embodiment 1

FIG. 1 (a) is a schematic partial cross-sectional view of a combinationweigher according to Embodiment 1 of the present invention, as viewedfrom the front, and FIG. 1( b) is a schematic view of upper collectingchutes and weighing hoppers of the combination weigher, as viewed fromabove.

The combination weigher includes two weighing units W1, W2, a lowercollecting chute 8 disposed below the weighing units, a lower collectinghopper 9 provided at a discharge outlet of a bottom part of the lowercollecting chute 8, and a control unit 20.

The two weighing units W1, W2 have the same configuration. Each of theweighing units W1, W2 is constructed in such a manner that a center basebody (body) 15 is disposed at a center of the weighing unit andsupported by four legs (not shown), and a dispersion feeder 1 having aconical shape is mounted to the upper part of the center base body(body) 15 to radially disperse objects to be weighed supplied from anexternal supplying device by vibration. Around the dispersion feeder 1,plural linear feeders 2 are provided to transfer the objects to beweighed which have been delivered from the dispersion feeder 1 intorespective feeding hoppers 3 by vibration. Plural feeding hoppers 3 andplural weighing hoppers 4 are disposed below the linear feeders 2 andare arranged in a circular form in such a manner that each feedinghopper 3 and each weighing hopper 4 correspond to the associated one ofthe linear feeders 2. The plural feeding hoppers 3 and the pluralweighing hoppers 4 are arranged circularly around the center base body15. The dispersion feeder 1, the linear feeders 2, the feeding hoppers 3and the weighing hoppers 4 are mounted to the center base body 15.Driving units (vibration devices for the dispersion feeder 1 and thelinear feeders 2, gate opening and closing devices for the feedinghoppers 3 and the weighing hoppers 4, etc) are accommodated within thecenter base body 15. Each weighing hopper 4 is attached with a weightsensor 41 such as a load cell for measuring the weight of the objects tobe weighed inside the weighing hopper 4. The weight sensor 41 isaccommodated along with the driving unit within the center base body 15.Each weight sensor 41 outputs the measured value to the control unit 20.

In the weighing units W1, W2, the upper collecting chutes 6A, 6B havingcircular upper openings and a substantially inverted truncated coneshape are disposed below the weighing hoppers 4 arranged circularly,respectively. Upper collecting hoppers 7 a, 7 b are provided atdischarge outlets 6Ae, 6Be of the bottom parts of the upper collectingchutes 6A, 6B, respectively. A group A is defined as a group of theweighing hoppers 4 belonging to the weighing unit W1. The objects to beweighed which have been discharged from the weighing hoppers 4 in thegroup A slide down on the upper collecting chute 6A, are held in theupper collecting hopper 7 a and thereafter are discharged therefrom.Likewise, a group B is defined as a group of the weighing hoppers 4belonging to the weighing unit W2. The objects to be weighed which havebeen discharged from the weighing hoppers 4 in the group B slide down onthe upper collecting chute 6B, are held in the upper collecting hopper 7b and thereafter are discharged therefrom.

As described above, each of the weighing units W1, W2 includes thedispersion feeder 1, the plural linear feeders 2, the plural feedinghoppers 3, the plural weighing hoppers 4 and weight sensors 41, theupper collecting chute (6A, 6B), the upper collecting hopper (7 a, 7 b),and the center base body 15. The same kinds of objects to be weighed aresupplied to the dispersion feeders 1 of the weighing units W1, W2, andthe same kinds of objects to be weighed are fed to all of the weighinghoppers 4 included in the combination weigher.

A single lower collecting chute 8 is disposed below the upper collectinghoppers 7 a, 7 b of the two weighing units W1, W2, and the lowercollecting hopper 9 is disposed at the discharge outlet of the bottompart of the lower collecting chute 8.

Below the lower collecting chute 8 of the combination weigher, forexample, a packaging machine (e.g., longitudinal pillow packagingmachine) having a single inlet as shown in FIG. 14 is disposed. Theobjects to be weighed which have been discharged from the lowercollecting hopper 9 are fed into the inlet (upper opening of a tube 51)of the packaging machine.

FIG. 14 is a schematic view showing an exemplary packaging machine(longitudinal pillow packaging machine) disposed below the combinationweigher.

While manufacturing package bags, the packaging machine charges into thepackage bags the objects to be weighed which have been discharged fromthe combination weigher and packages them. In this packaging machine, asheet of wrapping material 50 pulled out from a roll of a wrappingmaterial is caused to wind a tube 51 by a former 52 to form acylindrical shape, is suctioned by a pull-down belt unit 53 to bedelivered downwardly, and the joined vertical edges of the cylindricalwrapping material 50 are sealed (by fusion adhesion) by a verticalsealing machine 54. Then, the objects to be weighed which have beenweighed are charged into the cylindrical wrapping material 50 throughthe tube 51, and a horizontal sealing machine 55 positioned below thetube 51 seals horizontally across the upper end of a preceding bag andthe lower end of the following bag. This horizontal sealing enables thepreceding bag to be formed into a complete one with its upper and lowerends sealed, because the lower end of the preceding bag has been sealedby the previous horizontal sealing.

As should be appreciated from the above, in this Embodiment, thecombination weigher is configured such that the objects to be weighedwhich have been discharged from both of the collecting hoppers 7 a, 7 bare held in the lower collecting hopper 9 and thereafter are fed into asingle packaging machine inlet.

The control unit 20 controls the operation of the entire combinationweigher and performs a combination process to determine a combination(discharge combination) made up of the weighing hoppers 4 which shoulddischarge the objects to be weighed, from among the weighing hoppers 4in the groups A, B of the weighing units W1, W2. In the combinationprocess, the combination calculation is performed based on measuredvalues (measured values of the weights of the objects to be weighedinside the weighing hoppers 4, which are obtained using the weightsensors 41) of the weighing hoppers 4 holding the objects to be weighedwhose weights have been weighed by the weight sensors 41 to determineone combination made up of the weighing hoppers 4 in which a combinationweight value which is a total of the measured values falls within anallowable range (predetermined weight range) with respect to a targetweight value and the combination is determined as a dischargecombination. If combinations in which the combination weight values fallwithin the allowable range with respect to the target weight value areplural in number, then a combination in which, for example, a total ofthe measured values is closest to the target weight value (or acombination whose measured value coincides with the target weight value,if any). i.e., a combination in which an absolute value of a differencebetween the total of the measured values and the target weight value issmallest, is determined as a discharge combination. In the combinationweigher, the target weight value and an allowable range of the targetweight value are preset.

The outline of the operation of the combination weigher configured asdescribed above will be described.

An external supplying device supplies the objects to be weighed to eachdispersion feeder 1. The dispersion feeder 1 feeds the objects to beweighed to the feeding hopper 3 via the linear feeder 2. The feedinghopper 3 feeds the objects to be weighed to the weighing hopper 4. Theweight sensor 41 measures the weight of the objects to be weighed heldin the weighing hopper 4 and outputs the measured value to the controlunit 20. Then, the above mentioned combination process is performed todetermine the discharge combination. Then, the weighing hoppers 4selected to make up the discharge combination discharge the objects tobe weighed and the feeding hoppers 3 feed the objects to be weighed tothe weighing hoppers 4 which are empty. The linear feeders 2 feed theobjects to be weighed to the feeding hoppers 3 which are empty. Theobjects to be weighed which have been discharged from the weighinghoppers 4 slide down on the upper collecting chutes 6A, 6B, are held inthe upper collecting hoppers 7 a, 7 b and thereafter are discharged fromthe upper collecting hoppers 7 a, 7 b. The objects to be weighed slidedown on the lower collecting chute 8, are held in the lower collectinghopper 9, and thereafter are discharged to the packaging machine.

Subsequently, the operations in the case where discharge cycle times ofthe combination weigher are made different will be described. The term“discharge cycle time” as used herein refers to a discharge cycle inwhich the objects to be weighed are discharged from the weighing hoppers4 selected to make up the discharge combination. The operation in whichthe discharge cycle time is equal to an actual weighing cycle time isnamed a single shift operation. The operation in which the dischargecycle time is ½ of an actual weighing cycle time is named a double shiftoperation. The operation in which the discharge cycle time is ⅓ of anactual weighing cycle time is named a triple shift operation.

FIG. 2 is a timing chart showing an example of the opening and closingoperation of the gates of collecting hoppers, the opening and closingoperation of the gates of the weighing hoppers, and the operation of thehorizontal sealing device of the packaging machine, in a case where thecombination weigher of this Embodiment is configured to perform a singleshift operation.

The actual weighing cycle time Tr is, for example, a time period whichlapses immediately after a discharge combination is determined in acombination process performed in a previous weighing cycle, weighinghoppers 4 selected to make up the discharge combination discharge theobjects to be weighed, the objects to be weighed are next fed to theseweighing hoppers 4 belonging to the discharge combination, time forstabilizing the associated weight sensors 41 lapses, these weightsensors 41 measure the weights of the objects to be weighed, a next andearliest combination process is performed using at least the measuredvalues of these weighing hoppers 4, and then a discharge combination isdetermined. It is supposed that a weighing cycle time in a case where anallowance time, a wait time, etc, which elapses from when a dischargecombination is determined in a combination process, until weighinghoppers 4 selected to make up the discharge combination startdischarging of the objects to be weighed are zero is an ideal weighingcycle time T. Therefore, the ideal weighing cycle time T is, forexample, a time period taken to accomplish a procedure in which,weighing hoppers 4 selected to make up the discharge combinationdetermined in the combination process in the previous weighing cyclestart discharging of the objects to be weighed, the objects to beweighed are next fed to these weighing hoppers 4 belonging to thedischarge combination, time for stabilizing the associated weightsensors 41 lapses, these weight sensors 41 measure the weights of theobjects to be weighed, a next and earliest combination process isperformed using at least the measured values of these weighing hoppers4, and a discharge combination is determined. The ideal weighing cycletime is a time determined uniquely depending on the characteristic ofthe objects to be weighed, etc.

FIG. 2 shows an example in which the actual weighing cycle time Tr isequal to the ideal weighing cycle time T, that is, the combinationweigher is operated at a maximum speed, and discharge cycle time Td1associated with the weighing hopper 4 is equal to the actual weighingcycle time Tr (=T) and is equal to a packaging cycle time Tp1.

In the configuration for causing the combination weigher to perform thesingle shift operation, favorable weighing accuracy is achieved, forexample, by setting the number of the weighing hoppers 4 in each of thegroups A and B to five so that the total number of weighing hoppers 4 isten, and by setting the number of weighing hoppers 4 which would beselected in the combination process (number of the weighing hoppers 4which would be selected to make up the discharge combination) to four.The phrase “setting the number of weighing hoppers 4 which would beselected in the combination process to four” means that the operation ofthe linear feeder 2, and others is set so that a target feed amount ofthe objects to be weighed which are fed once from each feeding hopper 3to the associated weighing hopper 4 is approximately ¼ of the targetweight value.

In the single shift operation, once every actual weighing cycle time Tr(in this example, Tr=T), the combination process is performed, and theweighing hoppers 4 selected to make up the discharge combination in thecombination process discharge the objects to be weighed. Therefore, onceevery time Tr, the combination process is repeated, and the weighinghoppers 4 making up the discharge combination sequentially determineddischarge the objects to be weighed to the upper collecting chutes 6A,6B. Correspondingly, once every time Tr, both of the upper collectinghoppers 7 a and 7 b discharge the objects to be weighed simultaneously,and the lower collecting hopper 9 discharges the objects to be weighed.Thereby, the objects to be weighed are fed to the packaging machine onceevery actual weighing cycle time Tr.

Under the state where the combination weigher is operated continuously,the control unit 20 opens the gate of the lower collecting hopper 9 todischarge the objects be weighed to the packaging machine, in responseto, for example, a feed command signal received from the packagingmachine (time t1, t2, t3, . . . ).

In the configuration of FIG. 2, for example, the objects to be weighedwhich have been discharged from the weighing hopper 4 by opening of thegate at time t1 are collected into the upper collecting hopper 7 a, 7 band held therein until time t2, the objects to be weighed which havebeen discharged from the upper collecting hopper 7 a, 7 b by opening ofthe gate of the upper collecting hopper 7 a, 7 b at time t2 arecollected into the lower collecting hopper 9 and held therein until timet3, and discharged to the packaging machine by opening of the gate ofthe lower collecting hopper 9 at time t3. The objects to be weighedwhich have been discharged by opening of the gate of the lowercollecting hopper 9 at time t3 are fed to the packaging machine beforetime t3 a when the horizontal sealing device 55 of the packaging machinestarts the horizontal sealing, and horizontal sealing for sealing aportion corresponding to the upper end of the package bag starts at timet3 a.

In the example of FIG. 2, when the weighing hopper 4 opens the gateduring a time period ta, the objects to be weighed which have beendischarged from the weighing hopper 4 are fed to the upper collectinghopper 7 a, 7 b during a time period tb. When the upper collectinghopper 7 a, 7 b opens the gate during a time period tc, the objects tobe weighed which have been discharged from the upper collecting hopper 7a, 7 b are fed to the lower collecting hopper 9 during a time period td.When the lower collecting hopper 9 opens the gate during a time periodte, the objects to be weighed which have been discharged from the uppercollecting hopper 9 are fed to the packaging machine during a timeperiod tf. The packaging machine performs an operation in, for example,a fixed packaging cycle (Tp1). In the example of FIG. 2, during a timeperiod tg which is set not to coincide with the time period tf when theobjects to be weighed which have been discharged from the combinationweigher are fed to the packaging machine, the horizontal sealing device55 performs horizontal sealing.

By causing the combination weigher to perform the single shift operationas described above, the objects to be weighed are discharged to thepackaging machine once every time Tr.

Subsequently, the operation in the case where the combination weigher isconfigured to perform the double shift operation will be described indetail. In the configuration for causing the combination weigher toperform the double shift operation, for example, the number of theweighing hoppers 4 in each of the groups A and B may be set to seven sothat the total number of weighing hoppers 4 is fourteen, and the numberof weighing hoppers 4 which would be selected in the combination processmay be set to four. In this case, in the combination process performedrepetitively, four weighing hoppers 4 are selected from among about tenweighing hoppers 4, and weighing accuracy which is substantially as highas the weighing accuracy obtained in the case where the single shiftoperation is performed by setting the total number of weighing hoppers 4to ten and the number of objects to be weighed which would be selectedin the combination process to four.

FIG. 3 is a timing chart showing an example of the opening and closingoperation of the gates of collecting hoppers, the opening and closingoperation of the gates of the weighing hoppers, and the operation of thehorizontal sealing device of the packaging machine, in a case where thecombination weigher of this Embodiment of the present invention isconfigured to perform the double shift operation. As in the example ofFIG. 2, FIG. 3 shows an example in which the actual weighing cycle timeTr is equal to the ideal weighing cycle time T, that is, the combinationweigher is operated at a maximum speed, and the discharge cycle time Td2associated with the weighing hopper 4 is equal to ½ of the actualweighing cycle time Tr (=T) and is equal to a packaging cycle time Tp2.

In the double shift operation, once every time Tr/2, the combinationprocess is performed, and the weighing hoppers 4 selected to make up thedischarge combination in the combination process discharge the objectsto be weighed. Therefore, once every time Tr/2, the combination processis repeated, and the weighing hoppers 4 making up the dischargecombination sequentially determined discharge the objects to be weighedto the upper collecting chutes 6A, 6B. Correspondingly, once every timeTr/2, both of the upper collecting hoppers 7 a, 7 b discharge theobjects to be weighed simultaneously, and the lower collecting hopper 9discharges the objects to be weighed. Thereby, once every time Tr/2, theobjects to be weighed are fed to the packaging machine.

Under the state where the combination weigher is operated continuously,the control unit 20 opens the gate of the lower collecting hopper 9 todischarge the objects be weighed to the packaging machine, in responseto, for example, a feed command signal received from the packagingmachine (time t11, t12, t13, . . . ).

In the configuration of FIG. 3, for example, the objects to be weighedwhich have been discharged from the weighing hopper 4 by opening of thegate at time t11 are collected into the upper collecting hopper 7 a, 7 band held therein until time t12, the objects to be weighed which havebeen discharged from the upper collecting hopper 7 a, 7 b by opening ofthe gate of the upper collecting hopper 7 a, 7 b at time t12 arecollected into the lower collecting hopper 9 and held therein until timet13, and discharged to the packaging machine by opening of the gate ofthe lower collecting hopper 9 at time t13. The objects to be weighedwhich have been discharged by opening of the gate of the lowercollecting hopper 9 at time t13 are fed to the packaging machine beforetime t13 a when the horizontal sealing device 55 of the packagingmachine starts horizontal sealing, and horizontal sealing for sealing aportion corresponding to the upper end of the package bag starts at timet13 a.

By causing the combination weigher to perform the double shift operationas described above, the objects to be weighed are discharged to thepackaging machine once every time Tr/2, and a high-speed dischargeoperation at a speed which is twice times as high as the speed of thesingle shift operation is achieved. Thus, the combination weigher can beadapted to the packaging machine operating at a high speed.

The combination weigher of this Embodiment may be configured to performthe triple shift operation. In this case, a discharge cycle time (Td3)associated with the weighing hopper 4 is ⅓ of the actual weighing cycletime (Tr). In the triple shift operation, for example, the number ofweighing hoppers 4 in each of the groups A and B may be set to nine sothat the total number of weighing hoppers 4 is eighteen, and the numberof weighing hoppers 4 which would be selected in the combination processmay be set to four. In this case, in the combination process performedrepetitively, four weighing hoppers 4 are selected from among about tenweighing hoppers 4, and weighing accuracy which is substantially as highas the weighing accuracy obtained in the case where the single shiftoperation is performed by setting the total number of weighing hoppers 4to ten and the number of the objects to be weighed which would beselected in the combination process to four.

In the triple shift operation, once every time Tr/3, the combinationprocess is performed, and the weighing hoppers 4 selected to make up thedischarge combination in the combination process discharge the objectsto be weighed. Therefore, once every time Tr/3, the combination processis repeated, and the weighing hoppers 4 making up the dischargecombination sequentially determined discharge the objects to be weighedto the upper collecting chutes 6A, 6B. Correspondingly, once every timeTr/3, both of the upper collecting hoppers 7 a, 7 b discharge theobjects to be weighed simultaneously, and the lower collecting hopper 9discharges the objects to be weighed. Thereby, once every time Tr/3, theobjects to be weighed are fed to the packaging machine.

By causing the combination weigher to perform the triple shift operationas described above, the objects to be weighed are discharged to thepackaging machine once every time Tr/3 and a high-speed dischargeoperation at a speed which is three times as high as the speed of thesingle shift operation is achieved. Thus, the combination weigher can beadapted to the packaging machine operating at a high speed.

In order to maintain favorable weighing accuracy and improve a weighingspeed in the combination weigher as described above, it is necessary toincrease the total number of weighing hoppers 4 which participate incombination calculation.

Although the timings of the gate opening operations of the lowercollecting hopper 9, the upper collecting hoppers 7 a, 7 b and theweighing hoppers 4 are set equal in the above described example (FIG. 2,FIG. 3, etc), they may be set different. For example, the uppercollecting hopper 7 a, 7 b may start opening of the gate after the lowercollecting hopper 9 starts opening of the gate, or otherwise, theweighing hoppers 4 making up the discharge combination start opening ofthe gates after the upper collecting hopper 7 a, 7 b starts opening ofthe gate. In a case where a certain time is required from when theweighing hopper 4 starts discharging of the objects to be weighed untila head portion of a batch of the objects to be weighed reach thedischarge outlet (upper collecting hopper 7 a, 7 b) of the uppercollecting chute 6A, 6B, the weighing hopper 4 may open the gate alittle time before the upper collecting hopper 7 a, 7 b opens the gate.For example, the control unit 20 causes the lower collecting hopper 9 tostart opening of the gate after a predetermined time D1 (≧0) from whenthe feed command signal is received from the packaging machine, causesthe upper collecting hopper 7 a, 7 b to start opening of the gate aftera predetermined time D2 (≧0) from when the feed command signal isreceived, causes the weighing hopper 4 to start opening of the gateafter a predetermined time D3 (≧0) from when the feed command signal isreceived, and sets D1, D2, D3 as desired. Thus, the timings when thehoppers 4, 7 a, 7 b, 9 open the gates can be set as desired.

Alternatively, the control unit 20 may individually control the timingswhen the upper collecting hoppers 7 a, 7 b open the gates such that thetimings when the two upper collecting hoppers 7 a, 7 b start dischargingof the objects to be weighed are different a little. This makes itpossible to lessen the collision between the objects to be weigheddischarged from the upper collecting hopper 7 a and the upper collectinghopper 7 b, thereby preventing damage to the objects to be weighed.

FIG. 4( a) is a schematic view showing a specific positionalrelationship between the weighing hopper 4 and the upper collectingchute 6A, 6B and the configuration of the gate of the weighing hopper 4,and FIG. 4( b) is a schematic view showing a specific positionalrelationship between the upper collecting hopper 7 a, 7 b and the lowercollecting chute 8 and the configuration of the gate of the uppercollecting hopper 7 a, 7 b.

As shown in FIG. 4( a), the upper collecting chute 6A, 6B is positionednot to make contact with but to be closest to the weighing hopper 4. Thegate 4G of the weighing hopper 4 is one-side open gate which is adaptedto open in a direction in which the objects to be weighed fall down, asshown in FIG. 4( a). Since the weighing hopper 4 and the uppercollecting chutes 6A, 6B are configured as described above, the objectsto be weighed are discharged from the weighing hopper 4 smoothly ontothe upper collecting chute 6A, 6B upon opening of the gate 4G of theweighing hopper 4. Thus, the impact generated when the objects to beweighed which have been discharged from the weighing hopper 4 fall downonto the upper collecting chute 6A, 6B is mitigated, and therefore, thedamage to the objects to be weighed can be prevented. In addition,bouncing of the objects to be weighed which are falling down, etc, islessened, thereby reducing a time required for an upper collecting chutetransportation time period as will be described later.

Assuming that the weighing hoppers 4 are arranged circularly along theinner side of an imaginary circle in each weighing unit, the diameter ofthe upper opening of the upper collecting chute 6A, 6B can be made equalto or substantially equal to the diameter of the imaginary circle. Thesize (diameter) of the imaginary circle is determined by the number ofthe weighing hoppers 4 arranged and the arrangement pitch of theweighing hoppers 4. The number of the weighing hoppers 4 arranged isdetermined by the total number of the weighing hoppers 4 and the numberof weighing units in the combination weigher. The arrangement pitch ofthe weighing hoppers 4 is determined by the capacity (volume) of theweighing hopper 4 and a necessary spacing required between adjacentweighing hoppers 4, etc. As the capacity (volume) of the weighing hopper4 increases, the arrangement pitch increases.

As shown in FIG. 4( b), the positional relationship between the uppercollecting hopper 7 a, 7 b and the lower collecting chute 8 and theconfiguration of the gate of the upper collecting hopper 7 a, 7 b areidentical to those of the weighing hopper 4 and the upper collectingchute 6A, 6B shown in FIG. 4( a). Upon the gate 7G of the uppercollecting hopper 7 a, 7 b being opened, the objects to be weighed aredischarged from the upper collecting hopper 7 a, 7 b smoothly onto thelower collecting chute 8. Thus, the impact generated when the objects tobe weighed which have been discharged from the upper collecting hopper 7a, 7 b are falling down onto the lower collecting chute 8 is mitigated,and therefore, damage to the objects to be weighed is reduced. Inaddition, bouncing of the objects to be weighed which are falling downis lessened, thereby reducing a lower collecting chute transportationtime period as described later.

It is sufficient that the lower collecting chute 8 collects the objectsto be weighed discharged from the upper collecting hopper 7 a, 7 b intothe lower collecting hopper 9 at discharge outlet at the bottom partthereof. Therefore, the lower collecting chute 8 is easily formed by agutter-shaped member. For example, the lower collecting chute 8 includesa first gutter-shaped member for guiding the objects to be weighed whichhave been discharged from the upper collecting hopper 7 a to the lowercollecting hopper 9 and a second gutter-shaped member for guiding theobjects to be weighed which have been discharged from the uppercollecting hopper 7 b to the lower collecting hopper 9.

In this Embodiment, since the weighing hoppers 4 of a predeterminednumber in the combination weigher are separated into those belonging tothe plural weighing units W1, W2, the diameter of the upper opening andheight of each of the upper collecting chutes 6A, 6B can be made smallerthan those of the collecting chute 6 in the conventional example of FIG.13, if the arrangement pitch and the total number of the weighinghoppers 4 are both equal between them. For example, if the weighinghoppers 4 are arranged at a constant pitch, the diameter of the circle(e.g., the aforesaid imaginary circle) which is the arrangement shape ofthe weighing hoppers 4 in the case where nine weighing hoppers 8 arearranged circularly to form one of two circles is the half of thediameter of the circle which is the arrangement shape of the weighinghoppers 4 in the case where eighteen weighing hoppers 4 are arrangedcircularly at a constant pitch to form a single circle. In this case,the diameter of the upper collecting chutes 6A, 6B disposed below thegroups A, B each including the nine weighing hoppers arranged circularlycan be reduced to about half of the diameter of the collecting chute 6disposed below the eighteen weighing hoppers arranged circularly to froma single circle as shown in FIG. 13. In this case, if the tilting angleof the chute surface of the collecting chute is set equal, the height ofthe upper collecting chute 6A, 6B can be reduced to half of the heightof the collecting chute 6 of FIG. 13. In the same manner, if the tiltingangle of the chute surface of the collecting chute is set equal, theheight of the lower collecting chute 8 can be reduced to half of theheight of the collecting chute 6 of FIG. 13. The tilting angle of thechute surface of the collecting chute 6 of FIG. 13 is, for example,about 50 degrees. The tilting angle of the chute surface of each of theupper collecting chutes 6A, 6B, and the lower collecting chute 8 neednot be set to be equal to the tilting angle of the collecting chute 6 ofFIG. 13.

Since the size of the upper collecting chute 6A, 6B can be reduced asdescribed above, the transportation distance and transportation timeperiod of the objects to be weighed moving (sliding down) on the uppercollecting chute 6A, 6B can be reduced, and the objects to be weighedwhich have been discharged from the weighing hoppers 4 can be collectedinto the upper collecting hopper 7 a, 7 b before its batch length getslarge and can be held therein in a single lump state. For this reason,even in the objects to be weighed, having a characteristic in which itsbatch time on the collecting chute tends to be long, even in the casewhere the total number of the weighing hoppers 4 is large, or even inthe case where the volume of the weighing hopper 4 is large and thearrangement pitch of the weighing hoppers 4 must be set longer, it ispossible to reduce the batch time (e.g., time required for a time periodtb of FIG. 2) of the objects to be weighed on the upper collecting chute6A, 6B. As used herein, the term “batch time” of the objects to beweighed on the upper collecting chute 6A, 6B refers to a time periodfrom when a head portion of a batch of the objects to be weighed whichhave been discharged from the weighing hoppers 4 making up the dischargecombination to the upper collecting chute 6A, 6B reach a dischargeoutlet (collecting hopper 7 a, 7 b) of the upper collecting chute 6A, 6Buntil a tail portion of a batch of the objects to be weighed reach thedischarge outlet (collecting hopper 7 a, 7 b) of the upper collectingchute 6A, 6B.

Since the upper collecting hoppers 7 a, 7 b are provided at thedischarge outlets of the upper collecting chutes 6A, 6B, respectively,the objects to be weighed can be discharged to the lower collectingchute 8 in a lump state. Thus, since the objects to be weighed can bedischarged in a lump state from the upper collecting hoppers 7 a, 7 bonto the lower collecting chute 8, and the size of the lower collectingchute 8 is reduced, the transportation distance and transportation timeperiod of the objects to be weighed moving (sliding down) on the lowercollecting chute 8 can be reduced, and the objects to be weighed whichhave been discharged from the upper collecting hoppers 7 a, 7 b can becollected into the lower collecting hopper 9 before its batch lengthgets large and can be held therein in a lump state. For this reason,even in the objects to be weighed, having a characteristic in which itsbatch time on the collecting chute tends to be long, even in the casewhere the total number of the weighing hoppers 4 is large, or even inthe case where the volume of the weighing hopper 4 is large and thearrangement pitch of the weighing hoppers 4 must be set longer, it ispossible to reduce the batch time (e.g., time required for a time periodtd of FIG. 2) of the objects to be weighed on the lower collecting chute8. Furthermore, because of the presence of the lower collecting hopper9, the objects to be weighed can be discharged in a lump state into aninlet of the packaging machine. As used herein, the term “batch time” ofthe objects to be weighed on the lower collecting chute 8 refers to atime period from when a head portion of a batch of the objects to beweighed which have been discharged from the upper collecting hopper 7 a,7 b to the lower collecting chute 8 reach a discharge outlet (collectinghopper 9) of the lower collecting chute 8 until a tail portion of abatch of the objects to be weighed reach the discharge outlet(collecting hopper 9) of the lower collecting chute 8.

As should be understood from above, the batch time of the objects to beweighed on each of the upper and lower collecting chutes can be reduced,regardless of the characteristic of the objects to be weighed, the totalnumber of the weighing hoppers 4, etc, thereby enabling a high-speedoperation. By setting the batch time (tb, td) of the objects to beweighed on each of the upper and lower collecting chutes to a time whichis not longer than a certain time (allowable batch time) assumed foreach shift operation and each collecting chute, in the configuration forcausing the combination weigher to perform the above mentioned operationsuch as the single shift operation, the double shift operation or thetriple shift operation, thereby enabling a high-speed operation withoutdecreasing the operation speed.

The phrase “allowable batch time assumed for each shift operation andeach collecting chute is, for example, a time obtained by subtracting abatch inhibiting time S which is a certain time predetermined for eachcollecting chute from a desired discharge cycle time (Td1, Td2, Td3) foreach shift operation. In this case, by setting a desired discharge cycletime Td1=T (ideal weighing cycle time) when the combination weigherperforms the single shift operation, the operation at a maximum speed isachieved. In the same manner, by setting a desired discharge cycle timeTd2=T/2 when the combination weigher performs the double shiftoperation, the operation at a maximum speed is achieved, while bysetting a desired discharge cycle time Td3=T/3 when the combinationweigher performs the triple shift operation, the operation at a maximumspeed is achieved. In the configuration of FIG. 1, for example, thebatch inhibiting time S for the upper collecting chute 6A, 6B is a timeperiod when the gate of the upper collecting hopper 7 a, 7 b is open todischarge the objects to be weighed, while the batch inhibiting time Sfor the lower collecting chute 8 is a time period when the gate of thelower collecting hopper 9 is open to discharge the objects to beweighed. As described later, when the lower collecting hopper 9 isomitted, the batch inhibiting time S for the lower collecting chute 8 isset to a time which will not impede the operation (e.g., horizontalsealing operation) of the packaging machine located below. The batchtime of the objects to be weighed on each of the upper and lowercollecting chutes may be determined by conducting a test (e.g., testusing a test machine) using the objects to be weighed which are weighedby the combination weigher.

The collecting chutes and other members are designed and manufactured sothat the batch times of the objects to be weighed on the upper and lowercollecting chutes are not longer than the allowable batch times and theobjects to be weighed which are discharged previously are not mixed withthe objects to be weighed which are discharged next on each collectingchute.

For example, in the configuration for causing the combination weigher toperform the single shift operation, as shown in FIG. 2, when the gate ofthe weighing hopper 4 is opened during a time period ta (time periodfrom when the gate of the weighing hopper 4 starts opening, it is open,and until it is closed), the objects to be weighed which have beendischarged from the weighing hopper 4 are fed to the upper collectinghopper 7 a, 7 b during a time period tb. At time t2 just after a lapseof a time period α (hereinafter referred to as upper collecting chutetransportation time period) from when the gate of the weighing hopper 4starts opening until a portion of a batch of the objects to be weighedwhich reach the upper collecting hopper 7 a, 7 b last, are fed to theupper collecting hopper 7 a, 7 b, the gate of the upper collectinghopper 7 a, 7 b is opened to discharge the objects to be weighed. Inthis Embodiment, the upper collecting chutes 6A, 6B are configured sothat the upper collecting chute transportation time period α is notlonger than the discharge cycle time Td1 (=Tr). In this case, if theupper collecting chute transportation time period α is set much longerthan the discharge cycle time Td1, then there is a chance that twobatches of the objects to be weighed which have been discharged from theweighing hoppers 4 exist on the upper collecting chute 6A, 6B and aremixed, which is undesirable (event 1). The weighing speed is notincreased if the upper collecting chute transportation time period α isset shorter than the discharge cycle time Td1, leading to a situationwhere the moving speed of the objects to be weighed increases and theobjects to be weighed are more likely to be damaged (event 2). From anempirical rule, in light of the event 1, it is desired that the uppercollecting chute transportation time period α be set to a time which isnot longer than 1.1 times as long as the discharge cycle time Td1.Furthermore, in light of the event 2, it is desired that the uppercollecting chute transportation time period α be set to a time which iswithin a range of 0.9 to 1.1 times as long as the discharge cycle timeTd1. In light of the above, the upper collecting chutes 6A, 6B areconfigured so that the upper collecting chute transportation time periodα be set to a time which is not longer than 1.1 times as long as thedischarge cycle time Td1 (=Tr) and not shorter than 0.9 time as long asthe discharge cycle time Td1 (=Tr). For example, by making the slope ofthe chute surface of the upper collecting chute 6A, 6B steep, the uppercollecting chute transportation time period α is made shorter, whereasby making the slope gentle, the upper collecting chute transportationtime period α is made longer. It is sufficient that the discharge timeperiod (gate open time period of the upper collecting hopper 7 a, 7 b)tc when the objects to be weighed are discharged from the uppercollecting hopper 7 a, 7 b is set to a time period other than the timeperiod tb when the objects to be weighed are fed to the upper collectinghopper 7 a, 7 b. When the upper collecting chute transportation timeperiod α is longer than the discharge cycle time Td1 and is not longerthan 1.1 times as long as the discharge cycle time Td1, for example, thecontrol unit 20 controls the weighing hopper 4 so that its gate startsopening before the gate of the upper collecting hopper 7 a, 7 b startsopening.

The batch time (tb) of the objects to be weighed on the upper collectingchute 6A, 6B increases as the transportation distance (transportationtime period) of the objects to be weighed sliding down on the uppercollecting chute 6A, 6B increases. Therefore, as described above, byconfiguring the upper collecting chute 6A, 6B so that the uppercollecting chute transportation time period α is a time which is notlonger than 1.1 times as long as the discharge cycle time Td1, it ispossible to set the batch time (tb) of the objects to be weighed on theupper collecting chute 6A, 6B to the allowable batch time (Td1−tc) orshorter. In addition, since it is possible to avoid an event that theobjects to be weighed which are previously discharged from the weighinghoppers 4 and the objects to be weighed which are next discharged fromthe weighing hoppers 4 coexist at the same time on the upper collectingchute 6A, 6B, it is possible to surely prevent the previous batch ofobjects to be weighed from being mixed with the next batch of objects tobe weighed on the upper collecting chute 6A, 6B.

The lower collecting chute 8 may be configured in the same manner. To bespecific, the lower collecting chute 8 is configured such that the timeperiod (hereinafter referred to as lower collecting chute transportationtime period) β from when the gate of the upper collecting hopper 7 a, 7starts opening until a portion of the objects to be weighed which reachthe lower collecting hopper 9 last are fed to the lower collectinghopper 9 is set to a time which is not longer than 1.1 times as long asthe discharge cycle time Td1 (=Tr), and is not shorter than 0.9 time aslong as the discharge cycle time Td1 (=Tr). It is sufficient that thedischarge time period (gate open time period of the lower collectinghopper 9) te when the objects to be weighed are discharged from thelower collecting hopper 9 is set to a time period other than the timeperiod td when the objects to be weighed are fed to the lower collectinghopper 9.

The batch time (td) of the objects to be weighed on the lower collectingchute 8 increases as the transportation distance (transportation timeperiod) of the objects to be weighed sliding down on the lowercollecting chute 8 increases. Therefore, as described above, byconfiguring the lower collecting chute 8 so that the lower collectingchute transportation time period β to a time which is not longer than1.1 times as long as the discharge cycle time Td1, it is possible to setthe batch time (td) of the objects to be weighed on the lower collectingchute 8 to the allowable batch time (Td1−te) or shorter. In addition,since it is possible to avoid an event that the objects to be weighedwhich are previously discharged from the upper collecting hopper 7 a, 7b and the objects to be weighed which are next discharged from the uppercollecting hopper 7 a, 7 b exist at the same time on the lowercollecting chute 8, it is possible to surely prevent the previous batchof objects to be weighed from being mixed with the next batch of objectsto be weighed on the lower collecting chute 8.

As should be appreciated from the above, since the upper collectingchute 6A, 6B and the lower collecting chute 8 are configured based on adesired discharge cycle time, etc, it is possible to surely avoid mixingbetween the previous batch of objects to be weighed and the next batchof objects to be weighed on the upper collecting chute 6A, 6B and thelower collecting chute 8, and the operation at a desired discharge cycletime Td1 (=Tr) is achieved.

In the configuration for causing the combination weigher to perform thedouble shift operation, in the same manner, it is sufficient that theupper collecting chute 6A, 6B is configured such that the uppercollecting chute transportation time period is set to a time which isnot longer than 1.1 times as long as the discharge cycle time Td2(=Tr/2), and is not shorter than 0.9 time as long as the discharge cycletime Td2 (=Tr/2), and the lower collecting chute 8 is configured suchthat the lower collecting chute transportation time period is set to atime which is not longer than 1.1 times as long as the discharge cycletime Td2 (=Tr/2), and is not shorter than 0.9 time as long as thedischarge cycle time Td2 (=Tr/2). In the configuration for causing thecombination weigher to perform the triple shift operation, it issufficient that the upper collecting chute 6A, 6B is configured suchthat the upper collecting chute transportation time period is set to atime which is not longer than 1.1 times as long as the discharge cycletime Td3 (=Tr/3), and is not shorter than 0.9 time as long as thedischarge cycle time Td3 (=Tr/3), and the lower collecting chute 8 isconfigured such that the lower collecting chute transportation timeperiod is set to a time which is not longer than 1.1 times as long asthe discharge cycle time Td3 (=Tc/3), and is not shorter than 0.9 timeas long as the discharge cycle time Td3 (=Tr/3).

Having described above that the actual weighing cycle Tr is equal to theideal weighing cycle time T, the actual weighing cycle time Tr issometimes longer than the ideal weighing cycle time T. For example, whenthe ideal weighing cycle time T is 850 ms, the maximum weighing speed inthe single shift operation is 60000÷850=70 times/minute, the maximumweighing speed in the double shift operation is 140 times/minute, andthe maximum weighing speed in the triple shift operation is 210times/minute. In the operation at the maximum weighing speed, the actualweighing cycle time Tr is equal to the ideal weighing cycle time T. Tooperate the packaging machine at the maximum speed, for example, 120times/minute (packaging cycle time is 500 ms), it is sufficient that thecombination weigher achieves the weighing speed of 120 times/minute.Therefore, it is sufficient that the combination weigher is configuredto perform the double shift operation such that the discharge cycle timeTd2 (=Tr/2) is 500 ms. In this case, the actual weighing cycle time Tris 1000 ms. To operate the packaging machine at the maximum speed, forexample, 200 times/minute (packaging cycle time is 300 ms), it issufficient that the combination weigher achieves the weighing speed of200 times/minute. Therefore, it is sufficient that the combinationweigher is configured to perform the triple shift operation such thatthe discharge cycle time Td3 (=Tr/3) is 300 ms. In this case, the actualweighing cycle time Tr is 900 ms. Thus, the weighing speed of thecombination weigher is determined according to the maximum speed of thepackaging machine, and the collecting chute (6A, 6B, 8), etc isconfigured as described above based on the discharge cycle time or thelike according to the weighing speed. This enables the combinationweigher to operate at the weighing speed according to the maximum speedof the packaging machine and the packaging machine to operate at themaximum speed.

FIG. 5( a) is a schematic view showing an exemplary falling state of theobjects to be weighed inside the combination weigher and the packagingmachine in Embodiment 1, and FIG. 5( b) is a schematic view showing anexemplary falling state of the objects to be weighed inside theconventional combination weigher shown in FIG. 13 and the packagingmachine. In FIGS. 5( a) and 5(b), the objects to be weighed S1 indicatedby a broken line are objects to be weighed staying inside the weighinghopper 4.

As shown in FIG. 5( a), it is supposed that the objects to be weighed(one batch), for example, potato chips, fall down in succession from thelower collecting hopper 9 of the combination weigher of Embodiment 1 ata falling pitch C1 of 600 mm, and the length (hereinafter referred to aslength of a batch of the objects to be weighed) P1 from a head portionto a tail portion of a batch of the objects to be weighed which havebeen discharged from the lower collecting hopper 9 and are falling downinside the packaging machine is 200 nm. In this case, a distanceW1=C1−P1 between the batches of the objects to be weighed which arefalling down in succession is 400 mm. Assuming that the falling speed ofthe objects to be weighed is, for example, 1400 mm/second and constant,the time pitch at which the objects to be weighed are falling down is600 mm÷1400 mm/second=0.43 second, and the weighing speed of thecombination weigher is 60 second÷0.43 second/time=140 times/minute. Thefalling pitch of the objects to be weighed is a distance from the tailportion (or the head portion) of a batch of the objects to be weighed toa tail portion (or a head portion) of a next batch of the objects to beweighed.

To perform the horizontal sealing in the packaging machine, thehorizontal sealing device 55 is required to be operated to seize aportion of the rapping material 50 between the batches of the objects tobe weighed. Therefore, there is a chance that the objects to be weighedwill be stuck in a sealing portion of a package bag unless the distance(W1) between the batches of the objects to be weighed is about 200 mm ormore. In the example of FIG. 5( a), the objects to be weighed which havebeen lumped together by the lower collecting hopper 9 are dischargedtherefrom. This increases the distance between the batches of theobjects to be weighed, and therefore a time for horizontal sealingperformed by the packaging machine can be more easily ensured.

As shown in FIG. 5( b), the objects to be weighed which are dischargedfrom the collecting hopper 7 of the conventional combination weighershown in FIG. 13 have the falling pitch C1, the length P1 of a batch ofthe objects to be weighed, and the distance W1 between the batches ofobjects to be weighed, and the weighing speed of the combination weigheris 140 times/minute, similarly to the example of FIG. 5( a). However, inthis case, previous batch S3 of objects to be weighed overlaps with nextbatch S2 of objects to be weighed on the collecting chute 6. This isbecause as the sliding distance of the objects to be weighed which aresliding down on the collecting chute 6 increases, the length of a batchof the objects to be weighed which are sliding down on the collectingchute 6 increases. In the state where the batches of the objects to beweighed overlap with each other in this way, the objects to be weighedare stuck in the gate of the collecting hopper 7, regardless of thetiming when the gate is opened and closed. In addition, since one batchof objects to be weighed cannot clearly separated from other batch, itis difficult to correctly accommodate one batch of objects to be weighedinto a package bag. As a result, the weight of the objects to be weighedinside the package bag contains a substantial error, which is unsuitablefor practical use.

In the example shown in FIG. 5( b), if the length of a batch of theobjects to be weighed on the collecting chute 6 is not so large as thatshown in FIG. 5( b), there is a sufficient distance between the previousbatch S3 of objects to be weighed and the next batch S2 of objects to beweighed and therefore the collecting hopper 7 can perform the openingand closing operation of the gate without any interference and withoutthe objects to be weighed being stuck in the gate of the collectinghopper 7, then the object to be weighed will not be stuck in the gate ofthe collecting hopper 7 or the weight of the objects to be weighedinside the packaging machine will contain no error unlike in the exampleof FIG. 5( b). However, in this case, long before the previous batch ofobject to be weighed are made into a lump in the collecting hopper 7 andthe collecting hopper 7 starts discharging of the objects to be weighedto the packaging machine located below, the weighing hopper 4 must startdischarging of a next batch of objects to be weighed. This will notarise a problem when the packaging machine is operated stably withoutstopping, but will arise a severe problem when the packaging machine isstopped, because for example, the packaging machine has run out ofpackaging film or date print film. In this case, in the combinationweigher, since the weighing hopper 4 must discharge the next batch ofobjects to be weighed long before the collecting hopper 7 discharges theobjects to be weighed. Therefore, whenever the packaging machine stops,two batches of object to be weighed will stay inside the collectinghopper 7, and the weight of the objects to be weighed inside thepackaging machine will contain a substantial error if these two batchesare discharged to the packaging machine. Therefore, this case is notvirtually practical, either. Of course, the operation speed of thecombination weigher may be reduced and the weighing hopper 4 may beconfigured not to discharge the objects to be weighed until the gate ofthe collecting hopper 7 starts opening. But, a significant problem thatthe packaging machine cannot exhibit its highest ability will arise.

In contrast, in this Embodiment, the plural upper collecting chutes 6A,6B which have upper openings of a smaller diameter and a smaller heightand have a shorter sliding distance (transportation distance) of objectsto be weighed than the conventional collecting chute 6 are provided, thelower collecting chute 8 which collects the objects to be weighed whichare discharged from the upper collecting chutes 6A, 6B and along whichthe objects to be weighed slide down over a shorter distance than theconventional collecting chute 6 are provided, and the collecting hoppers7 a, 7 b, 9 are provided at discharge outlets of the collecting chutes6A, 6B, 8, respectively. In this case, since the sliding distances ofthe objects to be weighed inside the upper collecting chute 6A, 6B andthe lower collecting chute 8 are shorter than that of the conventionalcollecting chute 6, the objects to be weighed are held in the associatedcollecting hoppers 7 a, 7 b, 9, before the length of a batch of theobjects to be weighed gets large (before the batch length of the objectsto be weighed gets large), as compared to the conventional collectingchute 6. Therefore, unlike the example shown in FIG. 5( b), the objectto be weighed are prevented from being stuck in the gate of thecollecting hopper 7, and the weight of the objects to be weighed insidethe packaging machine does not contain a substantial error. In addition,when the previous batch S3 of objects to be weighed is made into a lumpin the collecting hopper 9, and the gate of the lower collecting hopper9 is opened in response to a feed command signal of the packagingmachine, the next batch S2 of objects to be weighed stay in the uppercollecting hopper 7 a, 7 b, and the still next batch S1 of objects to beweighed stay inside the weighing hopper 4. Therefore, the abovementioned problem that two batches of objects to be weighed stay in thecollecting hopper when the packaging machine stops will not arise.

Even in the case where the weighing hopper 4 is controlled to open thegate a little time before the upper collecting hopper 7 a, 7 b opens thegate, a problem that two batches of objects to be weighed stay in thecollecting hopper when the packaging machine stops as described abovecan be solved in such a manner that the weighing hopper 4 is configuredto open the gate in response to the feed command signal from thepackaging machine, and thereby the objects to be weighed are notdischarged from the weighing hopper 4 when the packaging machine stops.

As should be appreciated from the above, to achieve a desired weighingspeed (e.g., aforesaid 140 times/minute) in the conventional weigher inwhich, for example, all of the weighing hoppers 4 are arranged on acircumference as shown in FIG. 13, a next batch of objects to be weighedmust be sometimes discharged from the weighing hopper 4 in a time periodwhen a previous batch of objects to be weighed stay on the collectingchute 6 and on the collecting hopper 7. In this case, like thisEmbodiment, plural weighing units W1, W2 are provided such that all ofthe weighing hoppers 4 are divided into plural groups A and B which areeach disposed on a single circumference and small upper collectingchutes 6A, 6B are provided, and the lower collecting chute 8 isprovided. The upper collecting chute 6A, 6B is configured so that theupper collecting chute transportation time period is not longer than 1.1times as long as the discharge cycle time according to a desiredweighing speed, and the lower collecting chute 8 is configured so thatthe lower collecting chute transportation time period is not longer than1.1 times as long as the discharge cycle time. Thereby, the abovementioned problem can be solved.

Since the diameter of the upper opening of the upper collecting chute6A, 6B is smaller than that of the conventional collecting chute 6, thecurvature radius of the chute surface of the upper collecting chute 6A,6B is small. Thereby, the horizontal length of a batch of the objects tobe weighed which have been discharged from the weighing hopper 4 on theupper collecting chute 6A, 6B is reduced, and the length of a batch ofthe objects to be weighed which are sliding down is reduced. Thiscontributes to reduction of the upper collecting chute transportationtime period.

In the case where the objects to be weighed which are discharged fromthe weighing hoppers 4 making up the discharge combination are collectedinto M (M is plural number and is 2 in the configuration of FIG. 1)upper collecting hoppers 7 a, 7 b, the amount of objects to be weighedcollected into the upper collecting hoppers 7 a, 7 b is UM in average ascompared to the case where the objects to be weighed are collected intoa single collecting hopper (FIG. 13) in the conventional example. Thus,it is possible to lessen bouncing or the like of the objects to beweighed at the collision between the objects to be weighed or at thecollision of the objects to be weighed against the inner wall of thecollecting hopper. This contributes to reduction of the upper collectingchute transportation time period.

Since the transportation distance over which the objects to be weighedslide down on each of the upper collecting chutes 6A, 6B and the lowercollecting chute 8 is short, the maximum speed at the sliding down issuppressed to a low one. Thus, the impact generated when the objects tobe weighed collide with each other, or the impact generated when theobjects entering the collecting hopper 7 a, 7 b, 9 collide against theinner wall of the collecting hopper is mitigated, thereby preventing thedamage to the objects to be weighed. The fact that the maximum speed ofthe objects to be weighed which are sliding down is suppressed to a lowone, contributes to lessening of bouncing or the like at the collisionbetween the objects to be weighed or at the collision of the objects tobe weighed against the inner wall of the collecting hopper, and hence toreduction of the upper collecting chute transportation time period andthe lower collecting chute transportation time period.

Furthermore, in this Embodiment, as described above, since the diameterof the upper opening of each of the upper collecting chutes 6A, 6B canbe reduced to about a half of that of the conventional example of FIG.13, if the arrangement pitch of the weighing hoppers 4 and the totalnumber of the weighing hoppers 4 are the same. Therefore, theinstallation area of the combination weigher can be reduced to about ahalf of that of the conventional example of FIG. 13.

In this Embodiment, if the batch length of a batch of the objects to beweighed which are discharged from the upper collecting hopper 7 a, 7 bonto the lower collecting chute 8 is sufficiently small, the length of abatch of the objects to be weighed which are discharged from thedischarge outlet at the bottom part of the lower collecting chute 8 canbe made small without the lower collecting hopper 9 and the packagingoperation of the packaging machine is not impeded without the lowercollecting hopper 9, the lower collecting hopper 9 may be omitted. Inthis case, the objects to be weighed which have been discharged from theupper collecting hopper 7 a, 7 b are discharged to the inlet of thepackaging machine through the lower collecting chute 8. Because of theomission of the lower collecting hopper 9, the configuration issimplified and the control therefor becomes unnecessary.

In this Embodiment, the size (volume) of the upper collecting hoppers 7a, 7 b can be reduced, by configuring the setting in the combinationprocess so that at least one weighing hopper 4 is selected without failfrom those belonging to each of the groups A, B respectivelycorresponding to the upper collecting chutes 6A, 6B to make up thedischarge combination, or a maximum number of the weighing hoppers 4selected from those belonging to each of the groups A and B is limitedto less than the number of the weighing hoppers 4 which would beselected. For example, when four weighing hoppers 4 are selected to makeup the discharge combination (when the number of weighing hoppers 4which would be selected is four), combination calculation is performedunder a condition in which at least one weighing hopper 4 is selectedwithout fail from those belonging to each of the groups A, B, or amaximum number of the weighing hoppers 4 which are selected from thosebelonging to each of the groups A, B is three. If such a condition isnot set, then the upper chute collecting hopper 7 a, 7 b is required tohave a volume for accommodating the objects to be weighed which havebeen discharged from the four weighing hoppers 4. However, if theaforesaid condition is set, the number of weighing hoppers 4 whichdischarge the objects to be weighed to each of the upper collectingchutes 6A, 6B is three at maximum. Therefore, it is sufficient that eachof the upper collecting hoppers 7 a, 7 b is formed to have a volume foraccommodating the objects to be weighed from the three weighing hoppers4. In other words, by determining the discharge combination so that theobjects to be weighed which are held in the weighing hoppers 4 making upthe discharge combination for discharging of the objects to be weighedto the upper collecting chutes 6A, 6B are always discharged to the twoupper collecting chutes 6A, 6B, the size of the collecting hoppers 7 a,7 b can be reduced.

Although the combination weigher includes two weighing units W1, W2 inthe example shown in FIG. 1, it may include three or more weighing unitshaving a similar structure as shown in FIGS. 6( a) and 6(b), forexample.

FIGS. 6( a) and 6(b) are schematic views of exemplary combinationweighers each including three weighing units, showing the uppercollecting chutes and the weighing hoppers in the combination weighers,as viewed from above.

In the example shown in FIG. 6( a), three weighing units W1˜W3 arearranged adjacent each other in a planar arrangement. In this case, thegroups A˜C of the weighing hoppers in the weighing units W1˜W3 arearranged such that the centers of the circles which are the arrangementshapes of the weighing hoppers 4 are positioned at vertexes of anequilateral triangle shape, respectively, and according to this, thethree upper collecting chutes 6A˜6C are disposed such that the centersof circles which are their upper opening shapes are positioned atvertexes of the equilateral triangle, respectively. In the example shownin FIG. 6( b), the three weighing units W1˜W3 are aligned in astraight-line shape in a planar arrangement.

In both of the examples of FIGS. 6( a) and 6(b), the three weighingunits W1˜W3 each having a configuration similar to that of the weighingunits W1, W2 of FIG. 1 are provided, a single lower collecting chute 8is provided below the upper collecting hoppers 7 a˜7 c of the threeweighing units W1˜W3, and the lower collecting hopper 9 is provided atthe discharge outlet of the bottom part of the lower collecting chute 8.The upper collecting hoppers 7 a˜7 c are provided at discharge outlets6Ae˜6Ce of the upper collecting chutes 6A˜6C of the weighing unitsW1˜W3, respectively.

The control unit 20 (see FIG. 1) determines weighing hoppers 4 making upa discharge combination from among the weighing hoppers 4 in all of theweighing hopper groups A, B, C respectively corresponding to the threeweighing units W1˜W3.

In the configurations of FIGS. 6( a), 6(b), the objects to be weighedwhich have been discharged from the weighing hoppers 4 making up thedischarge combination slide down on the upper collecting chutes 6A˜6C,are held in the collecting hoppers 7 a˜7 c, and thereafter aredischarged therefrom. The objects to be weighed which have beendischarged from the upper collecting hoppers 7 a˜7 c slide down on thelower collecting chute 8, are held in the lower collecting hopper 9, andthereafter are discharged to the inlet of the packaging machine.

In the configurations of FIGS. 6( a) and 6(b), the diameter of the upperopening of each of the upper collecting chutes 6A, 6B, 6C can be reducedto about ⅓ of that of the conventional collecting chute 6 in theconventional example of FIG. 13, if the arrangement pitch and totalnumber of the weighing hoppers 4 are the same. Therefore, thetransportation distance and transportation time period of the objects tobe weighed which move on (slide down on) the upper collecting chutes 6A,6B, 6C can be reduced, and the installation area of the entirecombination weigher can be reduced to about ⅓. If the tilting angle ofthe chute surface of the collecting chute is set equal, the height ofthe upper collecting chutes 6A, 6B, 6C can be reduced to about ⅓ of theheight of the collecting chute 6 of FIG. 13.

In the configuration of FIG. 6( a), if the tilting angle of the chutesurface is set equal, the height of the lower collecting chute 8 can bereduced to about 0.4 time of the height of the collecting chute 6 ofFIG. 13. Therefore, a sum of the height of the lower collecting chute 8and the height of the upper collecting chute 6A, 6B, 6C can be madeshorter than the height of the collecting chute 6 of FIG. 13, and theheight of the entire combination weigher can be reduced.

In the configuration of FIG. 6( b), if the tilting angle of the chutesurface is set equal, the height of the lower collecting chute 8 can bereduced to about ⅔ of the height of the collecting chute 6 of FIG. 13.In this case, the height of the entire combination weigher issubstantially equal to that of the conventional example of FIG. 13.

In both of the configurations of FIGS. 6( a) and 6(b), thetransportation time period of the objects to be weighed which are movingdown (sliding down) on the lower collecting chute 8 can be reduced ascompared to the collecting chute 6 in the conventional example. In theconfiguration of FIG. 6( a), since the distances from the three uppercollecting hoppers 7 a˜7 c to the discharge outlet of the lowercollecting chute 8 and to the lower collecting hopper 9 provided at thedischarge outlet thereof can be made evenly short, the transportationtime period of the objects to be weighed which are discharged from thethree upper collecting hoppers 7 a˜7 c and are moving down on the lowercollecting chute 8 can be reduced.

In both of the examples of FIGS. 6( a) and 6(b), similarly to theexample of FIG. 1, the upper and lower collecting chutes 6A, 6B, 6C, 8may be configured according to the cases where the combination weigheris configured to perform the single shift operation, the combinationweigher is configured to perform the double shift operation, and thecombination weigher is configured to perform the triple shift operation,and based on discharge cycle times according to desired weighing speeds,etc.

In the examples of FIGS. 6( a) and 6(b), if the batch length of a batchof the objects to be weighed which are discharged from the uppercollecting hoppers 7 a˜7 b onto the lower collecting chute 8 issufficiently small, the length of a batch of the objects to be weighedwhich are discharged from the discharge outlet at the bottom part of thelower collecting chute 8 can be made small without the lower collectinghopper 9 and the packaging operation of the packaging machine is notimpeded without the lower collecting hopper 9, then the lower collectinghopper 9 may be omitted.

In the examples of FIGS. 6( a) and 6(b), the size of the uppercollecting hoppers 7 a, 7 b, 7 c can be reduced, by configuring thesetting in the combination process so that at least one weighing hopper4 making up the discharge combination is selected without fail fromthose belonging to two or more of the groups A, B and C respectivelycorresponding to the upper collecting chutes 6A, 6B and 6C, or a maximumnumber of the weighing hoppers 4 selected from those belonging to eachof the groups A, B and C is limited to less than the number of theweighing hoppers 4 which would be selected.

In the case where the three weighing units W1˜W3 are arranged adjacenteach other shown in FIG. 6( a), the weighing hoppers 4 may be arrangedas shown in FIG. 7.

In the example of FIG. 7, no weighing hopper 4 is disposed in a regionwhere the three weighing units W1˜W3 are arranged adjacent each otherand which is surrounded by the three weighing units W1˜W3. In otherwords, the groups A˜C of the weighing hoppers in the weighing unitsW1˜W3 are configured such that the centers of the circles which are thearrangement shapes of the weighing hoppers 4 are positioned on vertexesof the equilateral triangle and no weighing hopper 4 is disposed withinthe equilateral triangle. FIG. 7 illustrates a configuration in whicheach of the weighing units W1˜W3 includes six weighing hoppers 4 and thetotal number of weighing hoppers 4 is eighteen. In this case, forexample, the size of the upper collecting chutes 6A, 6B, 6C may bedetermined assuming that each of the weighing units W1˜W3 includes sevenweighing hoppers 4, six weighing hoppers 4 are arranged on acircumference on which seven weighing hoppers 4 are arranged, except forthe region where the three weighing units W1˜W3 are arranged adjacenteach other and which is surrounded by the three weighing units W1˜W3.For example, the six weighing hoppers 4 may be arranged at a pitch equalto the pitch at which seven weighing hoppers 4 are arranged. In thiscase, the diameter of the upper opening of the upper collecting chute6A, 6B, 6C is slightly larger than (7/6 of) that in the case where sixweighing hoppers 4 are arranged at the aforesaid pitch on an entirecircumference. But, no weighing hopper 4 and no feeding hopper 3 aredisposed in the region where the three weighing units W1˜W3 are arrangedadjacent each other and which is surrounded by the three weighing unitsW1˜W3. This facilitates a dismounting work or a mounting work of theweighing hoppers 4 and the feeding hoppers 3 when they are cleaned,repaired, etc.

In the example of FIG. 7, no weighing hopper 4 is disposed in the regionwhere the three weighing units W1˜W3 are arranged adjacent each other.Alternatively, the weighing hopper 4 in only one of two arbitraryweighing units adjacent each other is disposed in a region where theseweighing units are adjacent each other. In this case, by arranging theweighing hoppers 4 of adjacent weighing units such that they are notadjacent each other, a dismounting work or a mounting work of theweighing hoppers 4 and the feeding hoppers 3 is facilitated when theyare cleaned, repaired, etc.

In the example of FIG. 6( b), by arranging the weighing hoppers 4 ofadjacent weighing units such that they are not adjacent each other andare not opposite to each other in the region where the three weighingunits W1˜W3 are arranged adjacent each other, a dismounting work or amounting work of the weighing hoppers 4 and the feeding hoppers 3 isfacilitated when they are cleaned, repaired, etc. The same applies tothe configuration of FIG. 1.

In this Embodiment, it is desired that the weighing hoppers 4 in therespective weighing units be equal in number if possible, and if not, itis desired that a difference in number be one at the largest. In otherwords, when the total number of the weighing hoppers 4 in thecombination weigher is integer times as many as the number of weighingunits in the combination weigher, the numbers of the weighing hoppers 4in the respective weighing units are set equal. If not, then thedifference in the number of the weighing hoppers 4 between the weighingunits is set to one at the largest. For example, when the total numberof weighing hoppers 4 is fifteen and two weighing units W1, W2 areprovided, the weighing unit W1 includes eight weighing hoppers 4 and theweighing unit W2 includes seven weighing hoppers 4. In this case,firstly, the diameter of the circle which is the arrangement shape ofthe weighing hoppers 4 in the weighing unit W1 including more weighinghoppers 4 is determined, and according to this, the size (diameter ofthe upper opening) of the upper collecting chute is determined. Then, inthe weighing unit W2 including fewer weighing hoppers 4, the size of theupper collecting chute is set equal to the size of the upper collectingchute in the weighing unit W1, and seven weighing hoppers 4 are arrangedat, for example, an equal pitch on a circumference of a circle which isequal in diameter to the circle which is the arrangement shape of theweighing hoppers 4 in the weighing unit W1. This can equalize thetransportation distances and transportation time periods of the objectsto be weighed which have been discharged from the weighing hoppers 4 andare sliding down on the respective upper collecting chutes in both ofthe weighing units W1, W2.

Embodiment 2

FIG. 8 (a) is a schematic view of upper collecting chutes and weighinghoppers of a combination weigher according Embodiment 2 of the presentinvention, as viewed from above, and FIG. 8( b) is a schematic view ofupper, intermediate and lower collecting chutes of the combinationweigher, as viewed from the front.

FIG. 8 shows an exemplary combination weigher including four weighingunits, and is a schematic view of the upper collecting chutes and theweighing hoppers of the combination weigher as viewed from above.

In Embodiment 1, two stages, i.e., upper and lower collecting chutes areprovided, whereas in this Embodiment, three stages, i.e., upper,intermediate and lower collecting chutes are provided.

The combination weigher includes four weighing units W1˜W4 having thesame configuration as that of the weighing units W1, W2 of FIG. 1, twosets of intermediate collecting chutes 10 a, 10 b and intermediatecollecting hoppers 11 a, 11 b, the lower collecting chute 8, the lowercollecting hopper 9 and the control unit 20.

The groups A˜D of the weighing hoppers in the four weighing units W1˜W4are arranged such that the centers of the circles which are arrangementshapes of the weighing hoppers 4 are positioned at the vertexes of anequilateral square, and according to this, the centers of the circleswhich are their upper opening shapes of the four upper collecting chutes6A˜6D are positioned at the vertexes of the square.

The single intermediate collecting chute 10 a is provided below theupper collecting hoppers 7 a, 7 b of the two weighing units W1, W2, andthe intermediate collecting hopper 11 a is disposed at the dischargeoutlet of the bottom part of the intermediate collecting chute 10 a.Likewise, the single intermediate collecting chute 10 b is providedbelow the upper collecting hoppers 7 c, 7 d of the two weighing unitsW3. W4, and the intermediate collecting hopper 11 b is disposed at thedischarge outlet of the bottom part of the intermediate collecting chute10 b. Further, the single lower collecting chute 8 is provided below thetwo intermediate collecting hoppers 11 a, 11 b and the lower collectinghopper 9 is provided at the discharge outlet of the lower collectingchute 8. The upper collecting hoppers 7 a˜7 d are provided at dischargeoutlets 6Ae˜6De of the upper collecting chutes 6A˜6D of the weighingunits W1˜W4, respectively.

The specific positional relationship between the weighing hoppers 4 andthe upper collecting chutes 6A˜6D, and the configurations of gates ofthe weighing hoppers 4 are identical to those of FIG. 4( a) described inEmbodiment 1. Also, the positional relationship between the uppercollecting hoppers 7 a, 7 b and the intermediate collecting chute 10 aand the configurations of the gates of the upper collecting hoppers 7 a,7 b, the positional relationship between the upper collecting hoppers 7c, 7 d and the intermediate collecting chute 10 b and the configurationsof the gates of the upper collecting hoppers 7 c, 7 b, and thepositional relationship between the intermediate collecting hoppers 11a, 11 b and the lower collecting chute 8 and the configurations of thegates of the intermediate collecting hoppers 11 a, 11 b are identical tothe positional relationship between the upper collecting hoppers 7 a, 7b and the lower collecting chutes 8, and the configurations of the gatesof the upper collecting hoppers 7 a, 7 b shown in FIG. 4( b) describedin Embodiment 1.

The other constituents are identical to those of Embodiment 1 and willnot be described repetitively. In addition, the operation of thedispersion feeders 1, the linear feeders 2 and the feeding hoppers 3(see FIG. 1) included in the weighing units W1˜W4 are identical to thoseof Embodiment 1 and will not be described repetitively. As in Embodiment1, the same kinds of objects to be weighed are supplied to thedispersion feeders 1 (see FIG. 1) of the weighing units W1˜W4 and thesame kinds of objects to be weighed are fed to all of the weighinghoppers 4 included in the combination weigher.

The control unit 20 controls the operation of the entire combinationweigher and performs a combination process to determine a combination(discharge combination) made up of the weighing hoppers 4 which shoulddischarge the objects to be weighed, from among the weighing hoppers 4in the groups A˜D, as in Embodiment 1.

In this configuration, the objects to be weighed which have beendischarged from the weighing hoppers 4 making up the dischargecombination slide down on the upper collecting chutes 6A˜6D, are held inthe upper collecting hoppers 7 a˜7 d and thereafter are discharged fromthe upper collecting hoppers 7 a˜7 d. The objects to be weighed whichhave been discharged from the upper collecting hoppers 7 a, 7 b slidedown on the intermediate collecting chute 10 a and are held in theintermediate collecting hopper 11 a. In the same manner, the objects tobe weighed which have been discharged from the upper collecting hoppers7 c, 7 d slide down on the intermediate collecting chute 10 b and areheld in the intermediate collecting hopper 11 b. The objects to beweighed which have been discharged from the intermediate collectinghoppers 11 a, 11 b, slide down on the lower collecting chute 8, are heldin the lower collecting hopper 9 and thereafter are discharged from thelower collecting hopper 9 into, for example, the inlet of the packagingmachine shown in FIG. 14.

FIG. 9 is a timing chart showing an example of the opening and closingoperation of the gates of collecting hoppers, the opening and closingoperation of the gates of the weighing hoppers, and the operation of ahorizontal sealing device of a packaging machine, in a case where thecombination weigher of this Embodiment is configured to perform a tripleshift operation. FIG. 9 shows an example in which the actual weighingcycle time Tr is equal to the ideal weighing cycle time T, that is, thecombination weigher is operated at a maximum speed, and the dischargecycle time Td3 associated with the weighing hopper 4 is ⅓ of the actualweighing cycle time Tr (=T) and is equal to a packaging cycle time Tp3.

In the configuration for causing the combination weigher to perform thetriple shift operation, favorable weighing accuracy is achieved, forexample, by setting the number of the weighing hoppers 4 in each of thegroups A˜D in the weighing units W1˜W4 to five, by setting the totalnumber of weighing hoppers 4 to twenty, and by setting the number ofweighing hoppers 4 which would be selected in the combination process tofive.

In the triple shift operation, once every time Tr/3, the combinationprocess is performed, and the weighing hoppers 4 selected to make up thedischarge combination in the combination process discharge the objectsto be weighed. Therefore, once every time Tr/3, the combination processis repeated, and the weighing hoppers 4 making up the dischargecombination sequentially determined discharge the objects to be weighedto the upper collecting chutes 6A˜6D. Correspondingly, all of the uppercollecting hoppers 7 a˜7 d discharge the objects to be weighedsimultaneously once every time Tr/3, both of the intermediate collectinghoppers 11 a, 11 b discharge the objects to be weighed simultaneouslyonce every time Tr/3, and the lower collecting hopper 9 discharges theobjects to be weighed once every time Tr/3. Thereby, the objects to beweighed are fed to the packaging machine once every time Tr/3.

Under the state where the combination weigher is operated continuously,the control unit 20 opens the gate of the lower collecting hopper 9 anddischarges the objects be weighed to the packaging machine, in responseto, for example, a feed command signal received from the packagingmachine (time t21, t22, t23, . . . ).

In the configuration of FIG. 9, for example, the objects to be weighedwhich have been discharged from the weighing hopper 4 by opening of thegate at time t21 are collected into the upper collecting hopper 7 a˜7 dand held therein until time t22, the objects to be weighed which havebeen discharged from the upper collecting hopper 7 a˜7 d by opening ofthe gate at time t22 are collected into the intermediate collectinghopper 11 a, 11 b and held therein until time t23, the objects to beweighed which have been discharged from the intermediate collectinghopper 11 a, 11 b by opening of the gate of the intermediate collectinghopper 11 a, 11 b at time t23 are collected into the lower collectinghopper 9, are held therein until time t24, and are discharged to theinlet of the packaging machine by opening of the gate of the lowercollecting hopper 9 at time t24. The objects to be weighed which havebeen discharged by opening of the gate of the lower collecting hopper 9at time t24 are fed to the packaging machine before time t24 a when thehorizontal sealing device 55 of the packaging machine starts thehorizontal sealing, and horizontal sealing for sealing a portioncorresponding to the upper end of the package bag starts at time t24 a.

By causing the combination weigher to perform the triple shift operationas described above, the objects to be weighed are discharged to thepackaging machine once every time Tr/3 and a high-speed dischargeoperation which is three times as high as the speed of the single shiftoperation is achieved. Thus, the combination weigher can be adapted tothe packaging machine operating at a high speed.

The combination weigher of this Embodiment may be configured to performa fourth shift operation described below. As used herein, the “fourthshift operation” refers to an operation in which a discharge cycle timeis ¼ of an actual weighing cycle time. In other words, a discharge cycletime (Td4) associated with the weighing hopper 4 is ¼ of the actualweighing cycle time. In addition, it is also supposed that the actualweighing cycle time Tr is equal to the ideal weighing cycle time T.

In the configuration for causing the combination weigher to perform thefourth shift operation, favorable weighing accuracy is achieved, forexample, by setting the number of the weighing hoppers 4 in each of thegroups A and D to five, by setting the number of the weighing hoppers 4in each of the groups B and C to six, by setting the total number ofweighing hoppers 4 to twenty two, and by setting the number of weighinghoppers 4 which would be selected in the combination process to four.

In the fourth shift operation, once every time Tr/4, the combinationprocess is performed, and the weighing hoppers 4 selected to make up thedischarge combination in the combination process discharge the objectsto be weighed. Therefore, once every time Tr/4, the combination processis repeated, and the weighing hoppers 4 making up the dischargecombination sequentially determined discharge the objects to be weighedto the upper collecting chutes 6A˜6D. Correspondingly, all of the uppercollecting hoppers 7 a˜7 d discharge the objects to be weighedsimultaneously once every time Tr/4, all of the intermediate collectinghoppers 11 a, 11 b discharge the objects to be weighed simultaneouslyonce every time Tr/4, and the lower collecting hopper 9 discharges theobjects to be weighed once every time Tr/4. Thereby, the objects to beweighed are fed to the packaging machine once every time Tr/4.

By causing the combination weigher to perform the fourth shift operationas described above, the objects to be weighed are discharged to thepackaging machine once every time Tr/4 and a high-speed dischargeoperation at a speed which is four times as high as the speed of thesingle shift operation is achieved. Thus, the combination weigher can beadapted to the packaging machine operating at a high-speed.

Although the timings of the gate opening and closing operations of thelower collecting hopper 9, the intermediate collecting hoppers 11 a, 11b, the upper collecting hoppers 7 a˜7 d and the weighing hoppers 4 areset equal in the example (FIG. 9, etc), they may be set different. Forexample, the control unit 20 causes the lower collecting hopper 9 tostart opening of the gate after a predetermined time D11 (≧0) from whenthe feed command signal is received from the packaging machine, causesthe intermediate collecting hopper 11 a, 11 b to start opening of thegate after a predetermined time D12 (≧0) from when the feed commandsignal is received, causes the upper collecting hopper 7 a˜7 d to startopening of the gate after a predetermined time D13 (≧0) from when thefeed command signal is received, and causes the weighing hopper 4 tostart opening of the gate after a predetermined time D14 (≧0) from whenthe feed command signal is received, and sets D11, D12, D13, and D14 asdesired. In this way, the timings when the hoppers 4, 7 a˜7 d, 9, 11 a,11 b open their gates can be set as desired.

Alternatively, the control unit 20 may individually control the timingswhen the upper collecting hoppers 7 a, 7 b open and close their gatessuch that the timings when the two upper collecting hoppers 7 a, 7 bstart discharging of the objects to be weighed are different a little.This makes it possible to lessen the collision between the objects to beweighed discharged from the upper collecting hopper 7 a and the objectsto be weighed discharged from the upper collecting hopper 7 b and toprevent damage to the objects to be weighed. Likewise, the control unit20 may individually control the timings when the upper collectinghoppers 7 c, 7 d open and close their gates such that the timings whenthe two upper collecting hoppers 7 c, 7 d start discharging of theobjects to be weighed are different a little. This makes it possible tolessen the collision between the objects to be weighed discharged fromthe upper collecting hopper 7 c and the objects to be weighed dischargedfrom the upper collecting hopper 7 d and to prevent damage to theobjects to be weighed. Likewise, the control unit 20 may individuallycontrol the timings when the intermediate collecting hoppers 11 a, 11 bopen and close their gates such that the timings when the twointermediate collecting hoppers 11 a, 11 start discharging of theobjects to be weighed are different a little. This makes it possible tolessen the collision between the objects to be weighed discharged fromthe intermediate collecting hopper 11 a and the objects to be weigheddischarged from the intermediate collecting hopper 11 b and to preventdamage to the objects to be weighed.

In the configuration of FIG. 8, if the number of the weighing hoppers 4is equal between the weighing units, the diameter of the upper openingof each of the upper collecting chutes 6A, 6B, 6C, 6D can be reduced toabout ¼ of that of the conventional example of FIG. 13 and theinstallation area of the entire combination weigher can be reduced toabout ¼ of that of the conventional example of FIG. 13, if thearrangement pitch and total number of the weighing hoppers 4 are equalto those of the conventional example of FIG. 13. If the tilting angle ofthe chute surface of the collecting chute is set equal, the height ofthe upper collecting chutes 6A, 6B, 6C, 6D can be reduced to about ¼ ofthe height of the collecting chute 6 of FIG. 13. In the case where noweighing hopper 4 is provided in the region which is surrounded by thefour weighing units W1˜W4 to facilitate a mounting work or a dismountingwork of the weighing hoppers 4 and the feeding hoppers 3, the diameterof the upper opening of the upper collecting chute 6A˜6D is slightlylarger than (4/3 of) that in the case where the weighing hoppers 4 arearranged on an entire circumference. In this case, the weighing hopper 4in only one of arbitrary two weighing units located adjacent each othermay be disposed in a region where they are adjacent each other.

As described in Embodiment 1, it is desired that the weighing hoppers 4in the respective weighing units be equal in number if possible, and ifnot, it is desired that a difference in number be one at the largest. Inthe case where the weighing hoppers 4 in the respective weighing unitsare different in number, for example, the weighing hoppers 4 in each ofthe groups A and D is set to five and the weighing hoppers 4 in each ofthe groups B and C is set to six as illustrated in this Embodiment,firstly, the diameter of the circle which is the arrangement shape ofthe weighing hoppers 4 in the weighing units W2, W3 having the groups B,C including more weighing hoppers 4 is determined, and according tothis, the size (diameter of the upper opening) of the upper collectingchute 6B, 6C is determined. Then, in the weighing units W1, W4 havingthe groups A, D including fewer weighing hoppers 4, the size of theupper collecting chutes 6A, 6D is set equal to the size of the uppercollecting chutes 6B, 6C in the weighing units W2, W3, and five weighinghoppers 4 are arranged at, for example, an equal pitch on acircumference of a circle which is equal in diameter to the circle whichis the arrangement shape of the weighing hoppers 4 in each of theweighing units W2, W3. This can equalize the transportation distancesand transportation time periods of the objects to be weighed which havebeen discharged from the weighing hoppers 4 and are sliding down on therespective upper collecting chutes 6A˜6D in all of the weighing unitsW1˜W4.

In Embodiment 2, as in Embodiment 1, since the weighing hoppers 4 in thecombination weigher are separated into those belonging to the pluralweighing units W1˜W4, the diameter of the upper opening and height ofeach of the upper collecting chutes 6A˜6D can be made smaller than thoseof the collecting chute 6 in the conventional example of FIG. 13, if thearrangement pitch and the total number of the weighing hoppers 4 areequal to those of the conventional example of FIG. 13. Since the size ofthe upper collecting chutes 6A˜6D can be reduced as described above, thetransportation distance and transportation time period of the objects tobe weighed which are moving down (sliding down) on the upper collectingchutes 6A˜6D can be reduced, and the objects to be weighed which havebeen discharged from the weighing hoppers 4, can be collected into theupper collecting hoppers 7 a˜7 d in a state where its batch length isstill small and can be held therein in a lump state. For this reason,even in the objects to be weighed, having a characteristic in which itsbatch time on the collecting chute tends to be long, even in the casewhere the total number of the weighing hoppers 4 is large, or even inthe case where the capacity of the weighing hopper 4 is large andtherefore the arrangement pitch of the weighing hoppers 4 must be setlonger, it is possible to reduce the batch time of the objects to beweighed on the upper collecting chutes 6A˜6D.

As in the lower collecting chute 8 of Embodiment 1, since the objects tobe weighed are discharged in a lump state to the intermediate collectingchutes 10 a, 10 b and the lower collecting chute 8 from the collectinghoppers 7 a˜7 d and 11 a, 11 b which are located thereabove, and thesize of the intermediate collecting chutes 10 a, 10 b, and the size ofthe lower collecting chute 8 are reduced, it is possible to reduce thetransportation distance and transportation time period of the objects tobe weighed which are moving down (sliding down) on each of thecollecting chutes 10 a, 10 b, 8. And, even in the objects to be weighed,having a characteristic in which its batch time on the collecting chutetends to be long, even in the case where the total number of theweighing hoppers 4 is large, or even in the case where the capacity ofthe weighing hopper 4 is large and therefore the arrangement pitch ofthe weighing hoppers 4 must be set longer, it is possible to reduce thebatch time of the objects to be weighed on the intermediate collectingchutes 10 a, 10 b and the lower collecting chute 8. Furthermore, becauseof the presence of the lower collecting hopper 9, the objects to beweighed can be discharged to the packaging machine in a lump state.

As should be understood from the above, it is possible to reduce thebatch time of the objects to be weighed on each of the upper,intermediate and lower collecting chutes, regardless of thecharacteristic of the objects to be weighed, the number of the weighinghoppers 4, etc, thereby enabling a high-speed operation.

By setting the batch time of the objects to be weighed on each of theupper, intermediate and lower collecting chutes to a time which is notlonger than a certain time (allowable batch time) supposed for eachshift operation and each collecting chute, in the configuration in whichthe above mentioned operation such as the triple shift operation, thefourth shift operation, etc is performed, a high-speed operation withoutdecreasing the operation speed.

The allowable batch time supposed for each shift operation and eachcollecting chute is, for example, a time obtained by subtracting a batchinhibiting time S which is set for each collecting chute from a desireddischarge cycle time (Td3, Td4) for each operation. In this case, bysetting a desired discharge cycle time Td3=T/3 (T: ideal weighing cycletime) when the triple shift operation is performed, the operation at amaximum speed is achieved. Likewise, by setting a desired dischargecycle time Td4=T/4 when the fourth shift operation is performed, theoperation at a maximum speed is achieved. In the configuration of FIG.8, for example, the batch inhibiting time S for the upper collectingchutes 6A˜6D is a time period when the gates of the upper collectinghoppers 7 a˜7 d are open to discharge the objects to be weighed, thebatch inhibiting time S for the intermediate collecting chutes 10 a, 10b is a time period when the gates of the intermediate collecting hoppers11 a, 11 b are open to discharge the objects to be weighed, and thebatch inhibiting time S for the lower collecting chute 8 is a timeperiod when the gate of the lower collecting hopper 9 is open todischarge the objects to be weighed. As described later, if the lowercollecting hopper 9 is omitted, the batch inhibiting time S for thelower collecting chute 8 may be set to a time period which does notimpede the operation (e.g., horizontal sealing operation) of thepackaging machine located therebelow. The batch time of the objects tobe weighed for the upper, intermediate and lower collecting chutes maybe determined by, for example, conducting a test (e.g., test using atest machine) using the objects to be weighed which this combinationweigher will weigh.

The collecting chutes and other members are designed and manufactured sothat the batch time of the objects to be weighed on each of the upper,intermediate and lower collecting chutes is not longer than theallowable batch time and mixing on each collecting chute between theobjects to be weighed which are discharged previously and the objects tobe weighed which are discharged next is prevented, as described above.

Therefore, in this Embodiment, the upper collecting chutes 6A˜6D, theintermediate collecting chutes 10 a, 10 b and the lower collecting chute8 may be configured based on a desired discharge cycle time, etc,similarly to the upper collecting chutes 6A, 6B, and the lowercollecting chute 8 in Embodiment 1.

Having described above that the actual weighing cycle time Tr is equalto the ideal weighing cycle time T, the actual weighing cycle time Trmay be set longer than the ideal weighing cycle time T by determiningthe weighing speed of the combination weigher according to the maximumspeed of the packaging machine as described in Embodiment 1. Bydetermining the weighing speed of the combination weigher according tothe maximum speed of the packaging machine and by configuring the upper,intermediate and lower collecting chutes (6A˜6D, 10 a, 10 b, 8), etc,based on a discharge cycle time according to a weighing speed, etc, thecombination weigher can operate at the weighing speed according to themaximum speed of the packaging machine and the packaging machine canoperate at the maximum speed.

Since the transportation distance over which the objects to be weighedslide down on each of the upper collecting chutes 6A˜6D, theintermediate collecting chutes 10 a, 10 b and the lower collecting chute8 is short, the maximum speed of the objects to be weighed which aresliding down is suppressed to a low one. Thus, the impact generated whenthe objects to be weighed collide with each other, or the impactgenerated when the objects entering the collecting hoppers 7 a˜7 d, 11a, 11 b, 9 collide against the inner wall of these collecting hopper ismitigated, thereby preventing the damage to the objects to be weighed.

In Embodiment 2, as in Embodiment 1, the size of the upper collectinghoppers 7 a˜7 d can be reduced, by configuring the setting in thecombination process so that at least one weighing hopper 4 is selectedwithout fail from those of two or more of the groups A˜D of the pluralweighing hoppers 4 to make up the discharge combination, or a maximumnumber of the weighing hoppers 4 selected from those of each of thegroups A˜D is limited to less than the number of the weighing hoppers 4which would be selected. In the same manner, the size of theintermediate collecting hoppers 11 a, 11 b can be reduced, byconfiguring the setting so that at least one of the weighing hoppers 4selected to make up the discharge combination is selected without failfrom those of each of a first group set consisting of the groups A and Band a second group set consisting of the groups C and D, or by limitinga maximum number of the weighing hoppers 4 selected from those of eachof the two group sets to less than the number of the weighing hoppers 4which would be selected.

In this Embodiment, if the batch length of the objects to be weighed onthe lower collecting chute 8 is small, the length of a batch of theobjects to be weighed which are discharged from the discharge outlet atthe bottom part of the lower collecting chute 8 can be made smallwithout the lower collecting hopper 9 and the packaging operation of thepackaging machine is not impeded without the lower collecting hopper 9,the lower collecting hopper 9 may be omitted. In this case, the objectsto be weighed which have been discharged from the intermediatecollecting hopper 11 a, 11 b are discharged to the inlet of thepackaging machine via the lower collecting chute 8. Because of theomission of the lower collecting hopper 9, the configuration issimplified and the control therefor becomes unnecessary.

If the objects to be weighed can be directly fed from the intermediatecollecting hopper 11 a, 11 b to a single packaging machine inlet, thelower collecting chute 8 and the lower collecting hopper 9 may beomitted. For example, if the inlet of the packaging machine has an upperpart of a large area and its opening diameter is large, the intermediatecollecting chutes 10 a, 10 b may be configured such that the twointermediate collecting hoppers 11 a, 11 b are closer to the packagingmachine inlet to directly feed the objects to be weighed which have beendischarged from the intermediate collecting hoppers 11 a, 11 b to thepackaging machine inlet. In this case, because of the omission of thelower collecting chute 8 and the lower collecting hopper 9, theconfiguration is simplified, and the control for the lower collectinghopper 9 may be omitted, as in the above case where the lower collectinghopper 9 is not provided. It may be said that in this case, the twointermediate collecting chutes 10 a, 10 b serve as the lower collectingchute and the intermediate collecting hoppers 11 a, 11 b serve as thelower collecting hopper.

As in the configuration (FIG. 6( b)) in which the three weighing unitsW1˜W3 are aligned in a straight-line shape in Embodiment 1, the fourweighing units W1˜W4 may be aligned in a straight-line shape.

Also, as in Embodiment 1, a single lower collecting chute and a singlelower collecting hopper may receive the objects to be weighed which havebeen discharged from the upper collecting hoppers 7 a˜7 d of all of theweighing units W1˜W4 and may discharge them to the packaging machineinlet (e.g., FIG. 6( a)).

Although the two-stage collecting chute configuration, i.e., upper andlower collecting chutes has been described in Embodiment 1 and thethree-stage collecting chute configuration, i.e., upper, intermediateand lower collecting chutes has been described in Embodiment 2, thecollecting chutes may be provided in four or more stages in the samemanner. The number of stages of the collecting chutes may be determinedin view of the number, arrangement and the like of the weighing units.The number of weighing units may be determined in view of thecharacteristic of the objects to be weighed, the total number of theweighing hoppers 4, etc. For example, the number of the weighing unitsmay be set larger when the objects to be weighed whose batch time on thecollecting chute tends to be long is used, or when the total number ofthe weighing hoppers 4 is larger and therefore a diameter of a circularform formed by arranging all of the weighing hoppers 4 is larger.

In any case, since it is sufficient that the collecting chutes locatedbelow the upper collecting chutes in the weighing unit collect theobjects to be weighed which have been discharged from the collectinghopper located thereabove into the discharge outlet at the bottom partthereof, like the above mentioned lower collecting chute 8 of FIG. 1, asimple configuration may be achieved using gutter-shaped members.

Subsequently, a modification of the weighing units used in the aboveEmbodiments will be described.

FIG. 10 is a schematic view of upper collecting chutes and weighinghoppers of an exemplary combination weigher including a modification ofthe weighing units W1, W2 of FIG. 1, as viewed from above.

In the configuration of FIG. 10, no weighing hopper 4 is disposed in aregion where the two weighing units W1, W2 are adjacent in theconfiguration of FIG. 1. The weighing units W1, W2 are configured tohave groups A and B in which the weighing hoppers 4 are arranged in acircular-arc shape (C-shape). In this case, the two groups A, B of theweighing hoppers 4 are respectively groups which include the pluralweighing hoppers 4 arranged along the inner sides of two differentimaginary circles. In these groups, the two imaginary circles partiallyoverlap with each other and no weighing hopper 4 is disposed incircular-arc regions of the imaginary circles corresponding to theoverlapping region.

In the configuration of FIG. 10, the two center base bodies 15 of FIG. 1may be joined to each other to form a single center base body 15A. Thefeeding hoppers 3 (see FIG. 1) in each of the weighing units W1, W2 arearranged in the circular-arc form (C-shape) to correspond to theweighing hoppers 4. Above the center base body 15A, the two dispersionfeeders 1 and the plural linear feeders 2 shown in FIG. 1 are disposed.The linear feeders 2 may be arranged according to the arrangement of thefeeding hoppers 3 and each dispersion feeder 1 may be configured to feedthe objects to be weighed to the linear feeders 2.

In the configuration of FIG. 10, no weighing hopper 4 and no feedinghopper 3 are disposed in the region where the two weighing units W1, W2are adjacent. This facilitates a mounting work or a dismounting work ofthe weighing hoppers 4 and the feeding hoppers 3 when they are cleaned,repaired, etc. However, if the weighing hoppers 4 of a certain numberare arranged at constant intervals, it is necessary to increase thediameter of the imaginary circle as the area of the overlapping regionof the two imaginary circles increases. The diameter of the twoimaginary circles in the configuration of FIG. 1 in which the weighinghoppers 4 are arranged along the inner sides of the two imaginarycircles having no overlapping region can be reduced to a half of thediameter of a single imaginary circle (conventional imaginary circle)formed by arranging all of the weighing hoppers 4 along the inner sideof the conventional imaginary circle in the conventional example shownin FIG. 13, thereby reducing the size of the upper collecting chute. Toachieve at least 50% of a diameter reducing effect (to make the diameterof the two imaginary circles not larger than ¾ of the diameter of theconventional imaginary circle), it is desired that the center angles ofthe circular-arc regions corresponding to the overlapping region of thetwo imaginary circles be set to 120 degrees or smaller. This is the casewhere the diameters of the two imaginary circles are equal and thecenter angles of the above circular-arc regions is 120 degrees when thediameter of the two imaginary circles is ¾ of the diameter of theconventional imaginary circle.

The configurations of FIGS. 6( a), and 6(b) may be, in the same manner,such that no weighing hopper 4 is disposed in the regions where thethree weighing units W1, W2, W3 are adjacent each other. In this case,the three center base bodies 15 (see FIG. 1) may be joined to each otherto form a single center base body. In the same manner, in theconfiguration of FIG. 8, no weighing hoppers 4 may be disposed in theregions where the four weighing units W1, W2, W3, W4 are adjacent eachother. In this case, the four center base bodies 15 (see FIG. 1) arejoined to each other to form a single center base body. In theconfiguration of FIG. 8, for example, the two weighing units W1, W2 andthe two weighing units W3, W4 may be configured as shown in FIG. 10.

In the Figures associated with Embodiment 1 and Embodiment 2, theweighing units are drawn to be located adjacent each other with a gapbetween them. It is desirable to arrange the weighing units without agap (arrange the upper collecting chutes without a gap), because thedistance between the upper collecting hoppers in adjacent weighing unitsis short, the size of the collecting chutes (e.g., the lower collectingchute 8 of FIG. 1, FIG. 6( a), FIG. 6( b), FIG. 7, and FIG. 10, thelower collecting chutes 8 a, 8 b of FIG. 11, and the intermediatecollecting chutes 10 a, 10 b, the lower collecting chute 8, etc of FIG.8) disposed below the weighing units can be reduced, and thetransportation distance and transportation time period of the objects tobe weighed which are sliding down on these collecting chutes can bereduced. On the other hand, in the configuration in which there is smallgap between adjacent weighing units, a mounting work and a dismountingwork of the upper collecting chutes is facilitated when the uppercollecting chutes are cleaned, etc.

In Embodiment 1 and Embodiment 2, the weighing hoppers 4 in eachweighing unit are arranged in a circular form, or they are arrangedalong the circumferences of the imaginary circles, but variousalternations may be made. For example, in each weighing unit, theweighing hoppers 4 may be arranged in an annular shape including an ovalshape, or a polygon shape having convex portion such as a square shapeor a rectangular shape, instead of the circular form. According to thearrangement shape of the weighing hoppers 4, the feeding hoppers 3, thelinear feeders 2, the upper collecting chutes, and others may bearranged. Nonetheless, it is desirable to arrange the weighing hoppers 4on the circumference like Embodiment 1 and 2, because it is possible toequalize the transportation distances of the objects to be weighed whichhave been discharged from the respective weighing hoppers 4 on the uppercollecting chutes and to reduce a batch time of the objects to beweighed on the upper collecting chutes.

Although in Embodiment 1 and Embodiment 2, the objects to be weighedwhich have been discharged from the combination weigher are fed to thesingle packaging machine inlet, two packaging machines or a twin-typepackaging machine having two inlets may be disposed below thecombination weigher and the objects to be weighed which have beendischarged from the combination weigher may be fed alternately to thetwo packaging machine inlets (first and second packaging machineinlets). This configuration will be described with reference to FIG. 11.

FIG. 11 is a plan view showing a configuration of lower collectingchutes in a case where the objects to be weighed which have beendischarged from the combination weigher are fed alternately to twopackaging machine inlets.

For example, in the configuration of FIG. 1 in which the collectingchutes are provided in two stages, the single lower collecting chute 8and the single collecting hopper 9 provided below the two uppercollecting hoppers 7 a, 7 b are replaced by the two lower collectingchutes 8 a, 8 b provided with collecting hoppers 9 a, 9 b at dischargeoutlets 8 ae and 8 be, respectively, and the upper collecting hoppers 7a, 7 b are each configured to selectively discharge the objects to beweighed to one of the two lower collecting chutes 8 a, 8 b. The objectsto be weighed which have been discharged from the lower collectinghopper 9 a are fed to a first packaging machine inlet, while the objectsto be weighed which have been discharged from the lower collectinghopper 9 b are fed to a second packaging machine inlet. In this case,the control unit 20 controls the upper collecting hoppers 7 a, 7 b sothat the upper collecting hoppers 7 a, 7 b discharge the objects to beweighed alternately to the two lower collecting chutes 8 a, 8 b and aredischarged to the same lower collecting chute simultaneously every timethe weighing hopper 4 discharges the objects to be weighed. In thiscase, in response to the discharging of the objects to be weighed fromthe upper collecting hoppers 7 a, 7 b alternately to the two lowercollecting chutes 8 a, 8 b, the two lower collecting hoppers 9 a, 9 balternately discharge the objects to be weighed.

In this case, since it is sufficient that each of the two lowercollecting chutes 8 a, 8 b collects the objects to be weighed which havebeen discharged from the upper collecting hoppers 7 a, 7 b into thelower collecting hoppers (9 a, 9 h) provided at the discharge outlets ofthe bottom parts thereof, they can be simply constructed by usinggutter-shaped members. For example, the lower collecting chute 8 a isconstructed by using a first gutter-shaped member for guiding theobjects to be weighed which have been discharged from the uppercollecting hopper 7 a to the lower collecting hopper 9 a and a secondgutter-shaped member for guiding the objects to be weighed which havebeen discharged from the upper collecting hopper 7 b to the lowercollecting hopper 9 a. The lower collecting chute 8 b may be constructedin the same manner.

In the configuration of FIG. 6( b) in which three weighing units arealigned in a straight-line shape, the objects to be weighed can be fedto the two packaging machine inlets in the same manner. In theconfiguration of FIG. 6( a), the structure of the lower collectingchutes is complicated a little, but the objects to be weighed can be fedto the two packaging machine inlets in a similar manner by providing thetwo lower collecting chutes to form two discharge paths.

In the configuration of FIG. 8 in which the collecting chutes areprovided in three or more stages, the objects to be weighed can be fedto the two packaging machine inlets through two discharge paths. Thatis, when the collecting chutes are provided in m (m: 3 or more) stages,two sets of collecting chutes and collecting hoppers in (k+1)-th (k: anyvalue in a range from 1 to m−1) stage to m-th stage are provided so thatall of k-th stage collecting hoppers provided at discharge outlets ofthe k-th stage collecting chutes, among the collecting chutes in firststage (uppermost) to m-th stage (lowermost), may be configured todischarge the objects to be weighed selectively in one of the twodirections, and the objects to be weighed which have been dischargedalternately in the two directions from the k-th stage collecting hoppersare guided alternately to the two packaging machine inlets.

In the configuration in which the collecting chutes are provided in twostages or in three or more stages, if the two packaging machine inletsare in close proximity to each other, the lowermost collecting hoppermay be configured to discharge the objects to be weighed selectively inone of the two directions (two packaging machine inlets) and the controlunit 20 may be configured to control the lowermost collecting hopper toalternately discharge the objects to be weighed from the lowermostcollecting hopper to the two packaging machine inlets, instead of theabove mentioned configuration (e.g., configuration shown in FIG. 11).

Although in Embodiment 1 and Embodiment 2, the weighing hoppers 4 areexemplarily described as the combination hoppers which are hoppers(hoppers which participate in combination calculation) holding theobjects to be weighed whose weight values are used in the combinationcalculation, the combination hoppers are not limited to the weighinghoppers 4. FIGS. 12( a), 12(b), 12(c), and 12(d) are views schematicallyshowing other examples of hoppers such as the combination hoppers. Thecollecting chute 6X in FIGS. 12( a)˜12(d) corresponds to the uppercollecting chutes (6A˜6D) described in the above embodiments.

For example, as shown in FIG. 12( a), a memory hopper 5 may be disposedobliquely below each weighing hopper 4 and may participate incombination calculation. In this case, each weighing hopper 4 isconfigured to discharge the objects to be weighed selectively to thecollecting chute 6X or to the memory hopper 5. When the memory hopper 5is emptied, the weighing hopper 4 feeds the objects to be weighed to thememory hopper 5. The control unit 20 performs the combination process todetermine a combination (discharge combination) of hoppers which shoulddischarge the objects to be weighed, which are selected from among theplurality of weighing hoppers 4 and the plurality of memory hoppers 5,and causes the hoppers corresponding to the discharge combination todischarge the objects to be weighed onto the collecting chute 6X. As theweight of the objects to be weighed inside the memory hopper 5 which isused in the combination calculation in the combination process, theweight obtained by measurement in the weighing hopper 4 locatedthereabove is used.

As shown in FIG. 12( b), each memory hopper 5 may have two accommodatingchambers 5 a, 5 b. In this case, the weighing hopper 4 is configured todischarge the objects to be weighed selectively to the accommodatingchamber 5 a or to the accommodating chamber 5 b of the memory hopper 5,and is configured not to discharge the objects to be weighed to thecollecting chute 6X. The two accommodating chambers 5 a, 5 b of eachmemory hopper 5 are each configured to discharge the objects to beweighed independently. Combination calculation is performed usingweights of the objects to be weighed inside the accommodating chamber 5a, 5 b of each memory hopper 5. The accommodating chambers 5 a, 5 bparticipate in combination calculation but the weighing hopper 4 doesnot participate in the combination calculation. As the weights of theobjects to be weighed inside the accommodating chambers 5 a, 5 b,weights obtained by measurement in the weighing hopper 4 locatedthereabove are used. Each weighing hopper 4 can participate in thecombination calculation provided that the weighing hopper 4 and eitherone of the accommodating chambers 5 a, 5 b of the associated memoryhopper 5 are selected simultaneously to make up a combination. Forexample, when the weighing hopper 4 and the accommodating chamber 5 a ofthe associated memory hopper 5 are selected simultaneously, the objectsto be weighed inside the weighing hopper 4 are discharged onto thecollecting chute 6X through the accommodating chamber 5 a.

As shown in FIG. 12( c), each weighing hopper 4 may have two weighingchambers 4 a, 4 b. In this case, the feeding hopper 3 is configured todischarge the objects to be weighed selectively to the weighing chamber4 a or to the weighing chamber 4 b of the weighing hopper 4, and the twoweighing chambers 4 a, 4 b of the weighing hopper 4 are configured toindependently discharge the objects to be weighed. The combinationcalculation is performed using the weights of the objects to be weighedinside the weighing chambers 4 a, 4 b in each weighing hopper 4, and theweighing chambers 4 a, 4 b participate in combination calculation. Inthe weighing hopper 4 having the two weighing chambers 4 a, 4 b, whenone weighing chamber, for example, only the weighing chamber 4 a holdsthe objects to be weighed, the weight of the objects to be weighedinside the weighing chamber 4 a is measured by the weight sensor 41.When the weighing chamber 4 b is fed with the objects to be weighed, theweight sensor 41 measures the total weight of the objects to be weighedinside the two weighing chambers 4 a, 4 h. The control unit 20 performsthe combination calculation in such a manner that it calculates theweight of the objects to be weighed inside the weighing chamber 4 b bysubtracting the weight of the objects to be weighed inside the weighingchamber 4 a from the total weight of the objects to be weighed insidethe two weighing chambers 4 a, 4 b.

As shown in FIG. 12( d), each weighing hopper 4 may have two weighingchambers 4 a, 4 b, and the memory hopper 5 having the two accommodatingchambers 5 a, 5 b respectively corresponding to the weighing chambers 4a, 4 b of the weighing chamber 4 may be provided below the weighinghopper 4. In this case, the feeding hopper 3 is configured to dischargethe objects to be weighed selectively to the weighing chamber 4 a or tothe weighing chamber 4 b of the weighing hopper 4. The objects to beweighed inside the weighing chamber 4 a of the weighing hopper 4 aresent out to the accommodating chamber 5 a of the memory hopper 5, whilethe objects to be weighed inside the weighing chamber 4 b of theweighing hopper 4 are sent out to the accommodating chamber 5 b of thememory hopper 5. The combination calculation is performed using theweights of the objects to be weighed inside the accommodating chambers 5a, 5 b of the memory hopper 5, and the accommodating chambers 5 a, 5 bparticipate in the combination calculation, but the weighing hopper 4does not participate in the combination calculation. As the weights ofthe objects to be weighed inside the accommodating chambers 5 a, 5 b,the weights obtained by measurement and calculation associated with theweighing chambers 4 a, 4 b in the weighing hopper 4 located thereaboveare used. The weighing chambers 4 a, 4 b of the weighing hopper 4 canparticipate in combination calculation provided that the weighingchamber 4 a, 4 b and the associated accommodating chamber 5 a, 5 b areselected simultaneously to make up a combination. For example, when theassociated weighing chamber 4 a and accommodating chamber 5 a areselected simultaneously, the objects to be weighed inside the weighingchamber 4 a are discharged onto the collecting chute 6X through theaccommodating chamber 5 a.

In addition to the above, the configuration of the hoppers such as thecombination hoppers may be changed in various ways.

Although in the Embodiments 1 and 2, the control unit 20 is constitutedby a microcomputer, etc, it is not limited to being configured as thesingle control apparatus, but instead may be each configured to includea plurality of control apparatuses which are disposed in a distributedmanner and co-operate to control the operation of the combinationweigher.

Numerous modifications and alternative embodiments of the invention willbe apparent to those skilled in the art in view of the foregoingdescription. Accordingly, the description is to be construed asillustrative only, and is provided for the purpose of teaching thoseskilled in the art the best mode of carrying out the invention. Thedetails of the structure and/or function may be varied substantiallywithout departing from the spirit of the invention.

INDUSTRIAL APPLICABILITY

A combination weigher of the present invention is useful as acombination weigher which is coupled to a packaging machine operating ata high speed, etc.

1. A combination weigher comprising: plural weighing units each of whichincludes: a combination hopper group including plural combinationhoppers which are arranged annularly and fed with objects to be weighed;an upper collecting chute which is disposed below the combination hoppergroup and configured to collect the objects to be weighed which havebeen discharged from the combination hoppers and to discharge theobjects to be weighed from a discharge outlet at a bottom part thereof;and an upper collecting hopper which is provided at the discharge outletof the upper collecting chute and configured to hold the objects to beweighed which have been discharged from the discharge outlet of theupper collecting chute, and to then discharge the objects to be weighed;a collecting and discharge means which is configured to collect theobjects to be weighed which have been discharged from upper collectinghoppers of the plural weighing units and to discharge the objects to beweighed; and a control means which is configured to repetitivelyperform: a combination process in which combination calculation isperformed based on weights of the objects to be weighed which are heldin the combination hoppers in combination hopper groups of all of theweighing units to determine a combination of combination hoppers holdingthe objects to be weighed whose total weight falls within apredetermined weight range and the combination is determined as adischarge combination; a first discharge process for causing thecombination hoppers making up the discharge combination determined inthe combination process to discharge the objects to be weighed; and asecond discharge process for causing the upper collecting hoppers todischarge all of the objects to be weighed which have been dischargedfrom the combination hoppers and are held in the upper collectinghoppers.
 2. The combination weigher according to claim 1, wherein thecombination hopper groups in the respective weighing units includeplural combination hoppers arranged along inner sides of circumferencesof plural different imaginary circles.
 3. The combination weigheraccording to claim 2, wherein the combination hopper groups areconfigured such that the different imaginary circles partially overlapwith each other, and the combination hopper is not disposed incircular-arc regions of the imaginary circles corresponding to anoverlapping region of the imaginary circles.
 4. The combination weigheraccording to claim 1, wherein the control means is configured to performthe second discharge process such that all of the upper collectinghoppers discharge the objects to be weighed simultaneously.
 5. Thecombination weigher according to claim 1, wherein the collecting anddischarge means includes a single lower collecting chute which isdisposed below the upper collecting hoppers and configured to collectthe objects to be weighed which have been discharged from all of theupper collecting hoppers and to discharge the objects to be weighed froma discharge outlet at a bottom part thereof to a packaging machineinlet.
 6. The combination weigher according to claim 1, wherein thecollecting and discharge means includes: plural intermediate collectingchutes which are disposed below the upper collecting hoppers andconfigured to collect the objects to be weighed which have beendischarged from plural different upper collecting hoppers and todischarge the objects to be weighed from discharge outlets at bottomparts thereof; plural intermediate collecting hoppers which arerespectively provided at discharge outlets of the respectiveintermediate collecting chutes and to hold the objects to be weighedwhich have been discharged from the discharge outlets of theintermediate collecting chutes and to then discharge the objects to beweighed; and a single lower collecting chute which is disposed below theintermediate collecting hoppers and configured to collect the objects tobe weighed which have been discharged from all of the intermediatecollecting hoppers and to discharge the objects to be weighed from adischarge outlet at a bottom part thereof to a packaging machine inlet.7. The combination weigher according to claim 5, wherein the collectingand discharge means further includes a lower collecting hopper which isprovided at a discharge outlet of the lower collecting chute andconfigured to hold the objects to be weighed which have been dischargedfrom the discharge outlet of the lower collecting chute and to thendischarge the objects to be weighed.
 8. The combination weigheraccording to claim 1, wherein the collecting and discharge meansincludes collecting chutes in plural stages from second stage to p-th(p: integer of 4 or more) stage which are disposed below a first-stagecollecting chute consisting of the upper collecting chutes, andcollecting hoppers which are respectively provided at discharge outletsof bottom parts of the collecting chutes in the second stage to (p−1)-thstage, configured to hold the objects to be weighed which have beendischarged from the discharge outlets at the bottom parts of thecollecting chutes and to then discharge the objects to be weighed, thecollecting chute in q-th (q: integer in a range from 2 to p) stage isconfigured to collect the objects to be weighed which have beendischarged from collecting hoppers respectively provided at dischargeoutlets of plural collecting chutes in (q−1)-th stage and to dischargethe objects to be weighed from a discharge outlet at a bottom partthereof, and the objects to be weighed which have been discharged fromthe discharge outlet at the bottom part of the collecting chute in thep-th stage are fed to the packaging machine inlet.
 9. The combinationweigher according to claim 8, wherein the collecting and discharge meansfurther includes a collecting hopper which is provided at a dischargeoutlet of the collecting chute in the p-th stage and configured to holdthe objects to be weighed which have been discharged from the dischargeoutlet of the collecting chute in the p-th stage and to then dischargethe objects to be weighed.
 10. The combination weigher according toclaim 1, wherein the upper collecting hopper is configured to dischargethe objects to be weighed selectively in a first direction or in asecond direction; wherein the collecting and discharge means includes: afirst lower collecting chute which is disposed below the uppercollecting hoppers and configured to collect the objects to be weighedwhich have been discharged from all of the upper collecting hoppers inthe first direction and to discharge the objects to be weighed from adischarge outlet at a bottom part thereof to a first packaging machineinlet; and a second lower collecting chute which is disposed below theupper collecting hoppers and configured to collect the objects to beweighed which have been discharged from all of the upper collectinghoppers in the second direction and to discharge the objects to beweighed from a discharge outlet at a bottom part thereof to a secondpackaging machine inlet; and wherein the control means is configured tocause all of the upper collecting hoppers to discharge the objects to beweighed alternately in the first and second directions, whenrepetitively performing the second discharge process.
 11. Thecombination weigher according to claim 1, wherein the upper collectinghopper is configured to discharge the objects to be weighed selectivelyin a first direction or in a second direction; wherein the collectingand discharge means includes: plural first intermediate collectingchutes which are disposed below the upper collecting hoppers andconfigured to collect the objects to be weighed which have beendischarged from plural different upper collecting hoppers in the firstdirection and to discharge the objects to be weighed from dischargeoutlets at bottom parts thereof; plural second intermediate collectingchutes which are disposed below the upper collecting hoppers andconfigured to collect the objects to be weighed which have beendischarged from plural different upper collecting hoppers in the seconddirection and to discharge the objects to be weighed from dischargeoutlets at bottom parts thereof; plural first intermediate collectinghoppers which are respectively provided at the discharge outlets of thefirst intermediate collecting chutes and configured to hold the objectsto be weighed which have been discharged from the discharge outlets ofthe first intermediate collecting chutes and to then discharge theobjects to be weighed; plural second intermediate collecting hopperswhich are respectively provided at the discharge outlets of the secondintermediate collecting chutes and configured to hold the objects to beweighed which have been discharged from the discharge outlets of thesecond intermediate collecting chutes and to then discharge the objectsto be weighed; a first lower collecting chute which is disposed belowthe first intermediate collecting hoppers and configured to collect theobjects to be weighed which have been discharged from all of the firstintermediate collecting hoppers and to discharge the objects to beweighed from a discharge outlet at a bottom part thereof to a firstpackaging machine inlet; and a second lower collecting chute which isdisposed below the second intermediate collecting hoppers and configuredto collect the objects to be weighed which have been discharged from allof the second intermediate collecting hoppers and to discharge theobjects to be weighed from a discharge outlet at a bottom part thereofto a second packaging machine inlet; wherein the control means isconfigured to cause all of the upper collecting hoppers to discharge theobjects to be weighed alternately in the first and second directions,when repetitively performing the second discharge process.
 12. Thecombination weigher according to claim 1, wherein the collecting anddischarge means includes: plural intermediate collecting chutes whichare disposed below the upper collecting hoppers and configured tocollect the objects to be weighed which have been discharged from pluraldifferent upper collecting hoppers and to discharge the objects to beweighed from discharge outlets at bottom parts thereof; pluralintermediate collecting hoppers which are respectively provided at thedischarge outlets of the intermediate collecting chutes and configuredto hold the objects to be weighed which have been discharged from thedischarge outlets of the intermediate collecting chutes and to thendischarge the objects to be weighed selectively in a first direction orin a second direction; a first lower collecting chute which is disposedbelow the intermediate collecting hoppers and configured to collect theobjects to be weighed which have been discharged from all of theintermediate collecting hoppers in the first direction and to dischargethe objects to be weighed from a discharge outlet at a bottom partthereof to a first packaging machine inlet; and a second lowercollecting chute which is disposed below the intermediate collectinghoppers and configured to collect the objects to be weighed which havebeen discharged from all of the intermediate collecting hoppers in thesecond direction and to discharge the objects to be weighed from adischarge outlet at a bottom part thereof to a second packaging machineinlet; wherein the control means is configured to cause all of theintermediate collecting hoppers to discharge the objects to be weighedalternately in the first and second directions, when repetitivelyperforming the second discharge process.
 13. The combination weigheraccording to claim 10, wherein the collecting and discharge meansfurther includes two lower collecting hoppers which are provided atdischarge outlets of the first and second lower collecting chutes,respectively, and configured to hold the objects to be weighed whichhave been discharged from the discharge outlets of the lower collectingchutes and to then discharge the objects to be weighed.
 14. Thecombination weigher according to claim 1, wherein the upper collectinghopper is configured to discharge the objects to be weighed selectivelyin a first direction or in a second direction; wherein the collectingand discharge means further includes collecting chutes in plural stagesfrom second stage to p-th (p: integer of 4 or more) stage which aredisposed below a first-stage collecting chute consisting of the uppercollecting chutes, and collecting hoppers which are respectivelyprovided at discharge outlets at bottom parts of the collecting chutesin the second stage to (p−1)-th stage and configured to hold the objectsto be weighed which have been discharged from the discharge outlets atthe bottom parts of the respective collecting chutes and to thendischarge the objects to be weighed, the collecting chute in q-th (q:integer in a range from 2 to p) stage is configured to collect theobjects to be weighed which have been discharged from the collectinghoppers provided at discharge outlets of plural collecting chutes in(q−1)-th stage and to discharge the objects to be weighed from adischarge outlet at a bottom part thereof, the collecting chutes insecond stage to p-th stage are disposed so as to form a first dischargepath for guiding the objects to be weighed which have been dischargedfrom the upper collecting hopper in the first direction to a firstpackaging machine inlet and a second discharge path for guiding theobjects to be weighed which have been discharged from the uppercollecting hopper in the second direction to a second packaging machineinlet; and wherein the control means is configured to cause all of theupper collecting hoppers to discharge the objects to be weighedalternately in the first and second directions when repetitivelyperforming the second discharge process.
 15. The combination weigheraccording to claim 1, wherein the collecting and discharge meansincludes collecting chutes in plural stages from second stage to p-th(p: integer of 4 or more) stage which are disposed below a first-stagecollecting chute consisting of the upper collecting chutes, andcollecting hoppers which are respectively provided at discharge outletsat bottom parts of the collecting chutes in the second stage to (p−1)-thstage and configured to hold the objects to be weighed which have beendischarged from the discharge outlets at the bottom parts of therespective collecting chutes, and to then discharge the objects to beweighed, the collecting chute in q-th (q: integer in a range from 2 top) stage, among the collecting chutes in the plural stages, isconfigured to collect the objects to be weighed which have beendischarged from the collecting hoppers respectively provided atdischarge outlets of plural collecting chutes in (q−1)-th stage and todischarge the objects to be weighed from a discharge outlet at a bottompart thereof, k-th stage collecting hopper which is a collecting hopperprovided at a discharge outlet of the collecting chute in k-th (k: oneinteger in a range from 2 to p−1) stage is configured to discharge theobjects to be weighed selectively in the first direction or in thesecond direction, the collecting chutes in (k+1)-th stage to p-th stageare disposed an as to form a first discharge path for guiding theobjects to be weighed which have been discharged from the k-th stagecollecting hopper in the first direction to a first packaging machineinlet and a second discharge path for guiding the objects to be weighedwhich have been discharged from the k-th stage collecting hopper in thesecond direction to a second packaging machine inlet; and wherein thecontrol means is configured to cause all of the collecting hoppers ink-th stage to discharge the objects to be weighed alternately in thefirst and second directions when repetitively performing the seconddischarge process.
 16. The combination weigher according to claim 14,wherein the collecting and discharge means further includes a collectinghopper which is provided at a discharge outlet of the collecting chutein p-th stage and configured to hold the objects to be weighed whichhave been discharged from the discharge outlet of the collecting chutein p-th stage and to then discharge the objects to be weighed.
 17. Thecombination weigher according to claim 1, wherein the control means isconfigured to repetitively perform the combination process in such amanner that, in n (n: predetermined plural number) successivecombination processes, the combination calculation is performed based onweights of objects to be weighed which are held in combination hopperswhich are not selected to make up a discharge combination determined inprevious combination processes, in a next and earliest combinationprocess.
 18. The combination weigher according to claim 1, wherein thecontrol means is configured to determine the discharge combination suchthat the discharge combination includes the combination hoppersbelonging to at least two combination hopper groups.
 19. The combinationweigher according to claim 1, wherein the control means is configured torepetitively perform a series of processes including the combinationprocess, the first discharge process and the second discharge process,in a predetermined cycle, and the upper collecting chute is configuredsuch that a time period that elapses from when the combination hoppersmaking up the discharge combination determined in the combinationprocess start discharging of the objects to be weighed until all of thedischarged objects to be weighed pass through on the upper collectingchute and are fed to the upper collecting hopper is not longer than 1.1times as long as the predetermined cycle.
 20. The combination weigheraccording to claim 5, wherein the control means is configured torepetitively perform a series of processes including the combinationprocess, the first discharge process and the second discharge process,in a predetermined cycle; wherein the upper collecting chute isconfigured such that a time period that elapses from when thecombination hoppers making up the discharge combination determined inthe combination process start discharging of the objects to be weigheduntil all of the discharged objects to be weighed pass through on theupper collecting chute and are fed to the upper collecting hopper is notlonger than 1.1 times as long as the predetermined cycle; and whereinthe lower collecting chute is configured such that a time period thatelapses from when the upper collecting hopper starts discharging of theobjects to be weighed until all of the discharged objects to be weighedpass through on the lower collecting chute and are discharged from adischarge outlet at a bottom part of the lower collecting chute is notlonger than 1.1 times as long as the predetermined cycle.
 21. Thecombination weigher according to claim 6, wherein the control means isconfigured to repetitively perform a series of processes including thecombination process, the first discharge process and the seconddischarge process, in a predetermined cycle; wherein the uppercollecting chute is configured such that a time period that elapses fromwhen the combination hoppers making up the discharge combinationdetermined in the combination process start discharging of the objectsto be weighed until all of the discharged objects to be weighed passthrough on the upper collecting chute and are fed to the uppercollecting hopper is not longer than 1.1 times as long as thepredetermined cycle; the intermediate collecting chute is configuredsuch that a time period that elapses from when the upper collectinghopper starts discharging the objects to be weighed until all of thedischarged objects to be weighed pass through on the intermediatecollecting chute and are fed to the intermediate collecting hopper isnot longer than 1.1 times as long as the predetermined cycle; andwherein the lower collecting chute is configured such that a time periodthat elapses from when the intermediate collecting hopper startsdischarging of the objects to be weighed until all of the dischargedobjects to be weighed pass through on the lower collecting chute and aredischarged from a discharge outlet at a bottom part of the lowercollecting chute is not longer than 1.1 times as long as thepredetermined cycle.
 22. The combination weigher according to claim 8,wherein the control means is configured to repetitively perform a seriesof processes including the combination process, the first dischargeprocess and the second discharge process, in a predetermined cycle;wherein the first-stage collecting chute is configured such that a timeperiod that elapses from when the combination hoppers making up thedischarge combination determined in the combination process startdischarging of the objects to be weighed until all of the dischargedobjects to be weighed pass through on the first-stage collecting chuteand are fed to the upper collecting hopper is not longer than 1.1 timesas long as the predetermined cycle; wherein the collecting chute in q-thstage is configured such that a time period that elapses from when thecollecting hopper provided at the discharge outlet of the collectingchute in (q−1)-th stage starts discharging of the objects to be weigheduntil all of the discharged objects to be weighed pass through on thecollecting chute in q-th stage and are discharged from a dischargeoutlet at a bottom part of the collecting chute in q-th stage is notlonger than 1.1 times as long as the predetermined cycle.
 23. Thecombination weigher according to claim 10, wherein the control means isconfigured to repetitively perform a series of processes including thecombination process, the first discharge process and the seconddischarge process, in a predetermined cycle; wherein the uppercollecting chute is configured such that a time period that elapses fromwhen the combination hoppers making up the discharge combinationdetermined in the combination process start discharging of the objectsto be weighed until all of the discharged objects to be weighed passthrough on the upper collecting chute and are fed to the uppercollecting hopper is not longer than 1.1 times as long as thepredetermined cycle; wherein the first lower collecting chute isconfigured such that a time period that elapses from when the uppercollecting hopper starts discharging of the objects to be weighed in thefirst direction until all of the discharged objects to be weighed passthrough on the first lower collecting chute and are discharged from adischarge outlet at a bottom part of the first lower collecting chute isnot longer than (2×1.1) times as long as the predetermined cycle; andwherein the second lower collecting chute is configured such that a timeperiod that elapses from when the upper collecting hopper startsdischarging of the objects to be weighed in the second direction untilall of the discharged objects to be weighed pass through on the secondlower collecting chute and are discharged from a discharge outlet at abottom part of the second lower collecting chute is not longer than(2×1.1) times as long as the predetermined cycle.
 24. The combinationweigher according to claim 19, wherein the predetermined cycle is set toa time which is 1/k (k: 1 or plural number) of an actual weighing cycletime which is a time period from when the combination hoppers making upthe discharge combination determined in the combination process startdischarging of the objects to be weighed until a time just before aprocedure in which the combination hoppers making up the dischargecombination are next fed with the objects to be weighed, then a next andearliest combination process is performed using at least weights of theobjects to be weighed held in the combination hoppers making up thedischarge combination, and combination hoppers making up a dischargecombination determined in the next and earliest combination processstart discharging the objects to be weighed.
 25. The combination weigheraccording to claim 24, wherein the actual weighing cycle time is equalto an ideal weighing cycle time which is a time period from when thecombination hoppers making up the discharge combination determined inthe combination process start discharging of the objects to be weigheduntil the combination hoppers making up the discharge combination arenext fed with the objects to be weighed, then a next and earliestcombination process is performed using at least weights of the objectsto be weighed held in the combination hoppers making up the dischargecombination, and a discharge combination is determined in the next andearliest combination process.
 26. The combination weigher according toclaim 1, wherein when the number of the weighing units is x, the totalnumber of the combination hoppers included in all of the weighing unitsis y, and y/x is an integer, the combination hopper group in each of theweighing units is configured to consist of y/x combination hoppers, andwhen (z−1)<(y/x)<z (z: integer) is satisfied, the combination hoppergroup in a part of all of the weighing units is configured to consist ofz combination hoppers and the combination hopper group in the weighingunit other than the part of the all of the weighing units is configuredto consist of (z−1) combination hoppers.
 27. The combination weigheraccording to claim 1, wherein the respective upper collecting chutes arearranged without a gap between them.
 28. The combination weigheraccording to claim 1, wherein the respective upper collecting chutes arearranged with a gap between them.
 29. The combination weigher accordingto claim 2, wherein the imaginary circles are configured to be incontact with each other.
 30. The combination weigher according to claim1, wherein the same kinds of objects to be weighed are fed to thecombination hoppers in all of the weighing units.